Nonaqueous electrolyte battery

ABSTRACT

The present invention uses a mixture of spherical carbonaceous materials having different average particle sizes as an anode active material in an anode composite mixture layer of an anode. The spherical carbonaceous material of large particle size decreases the reaction with non-aqueous electrolyte solution to suppress the decrease in battery capacity, form clearances having suitable sizes in the anode composite mixture layer, and retain the non-aqueous electrolyte solution. The clearances in the anode composite mixture layer are efficiently filled with the carbonaceous material of small particle size while spaces capable of suitably retaining the non-aqueous electrolyte solution are left unfilled. Thus, the volume density of the anode composite mixture layer is improved and the battery capacity is increased. Accordingly, energy density can be increased without deteriorating battery characteristics.

TECHNICAL FIELD

The present invention relates to a non-aqueous electrolyte battery, andmore particularly to a non-aqueous electrolyte battery comprising acathode, an anode and a non-aqueous electrolyte, and the batterycharacteristics of which are extremely improved.

This application claims a priority based on Japanese Application No.2002-050216 filed on Feb. 26, 2002 and Japanese Patent Application No.2002-137775 filed on May 13, 2002, and these applications are applied tothis application by referring to them.

BACKGROUND ART

Secondary batteries that are light and have high energy densities havebeen hitherto progressively developed as power sources of portableelectronic devices such as note book type portable computers, portabletelephones, video cameras with VTRs (video tape recorders), etc. Assecondary batteries having high energy densities, lithium-ion secondarybatteries have been developed which use lithium, lithium alloys ormaterials capable of being doped with/dedoped from lithium ions as anodeactive materials, and metal oxides or metal sulfides as cathode activematerials. In lithium-ion secondary batteries, carbonaceous materialsare used for electrochemical, physical and mechanical reasons, andreasons of battery performances, cost, safety, etc.

As for the carbonaceous materials, non-graphitizable carbons havingamorphous structures or graphite are used. The graphite includes naturalgraphite and artificial graphite. The artificial graphite includesspherical graphite, massive graphite, fibrous graphite, etc. When thenatural graphite is employed as the anode active material of thelithium-ion secondary battery, the natural graphite can increase abattery capacity. However, the natural graphite is disadvantageously lowin its other battery characteristics and hardly treated uponmanufacturing a battery. On the other hand, the artificial graphite iseasily treated upon manufacturing a battery and large in lithium storageper unit mass or unit volume. Accordingly, the artificial graphite isexcellent as the anode active material of the lithium-ion secondarybattery.

The spherical graphite among the artificial graphite is called, forinstance, a mesophase graphite. Pitch or the like is heated to form aspherulite, what is called a mesophase and an unnecessary part of themesophase is dissolved by a solvent, heated and graphitized to obtainthe spherical graphite. The spherical graphite is also called MCMB, anacronym for mesophase carbon microbeads. The spherical graphite isproduced by a method in which, for instance, the spherulite is allowedto grow large and crystallize, then the crystallized product is heatedand pulverized, as well as the above-described method.

The above-described artificial graphite exhibits excellent batterycharacteristics when artificial graphite is used as an anode of thelithium-ion battery. However, the artificial graphite has a problem thata lithium storage per unit mass or unit volume is lower than that ofnatural graphite.

Further, with spherical graphite, the volume density of the anode isdecreased due to spaces generated when two or more spherical bodies areallowed to come into contact with each other, so that a battery capacityis hardly increased.

As a means for improving the volume density of the anode, there is amethod in which the range of small particle size in the particle sizedistribution of the artificial graphite is widened to increase theamount of fine powder. Thus, the fine powder increases the volumedensity of the anode. Specifically, a method for containing fineparticles of 0.3 μm or smaller in an anode active material is proposedin, for instance, Japanese Patent Application Laid-Open No. hei 11-3706.In this case, when the spherical graphite having the fine powderincreased is used for the anode, the spherical graphite is high in itsreactivity with electrolyte solution and high in its activity becausethe spherical graphite has a large surface area relative to the volumeof the anode. Thus, the battery safety is disadvantageouslydeteriorated. Although the fine powder is high in its reactivity withthe electrolyte solution, a battery capacity is low. Further, when thespaces are excessively filled with the fine powder in the anode, it isfeared that there is no space for retaining the electrolyte solution inthe anode, and the resistance of the anode side becomes high whichdeteriorate the battery characteristics. That is, the addition particlesthat are too small is not preferable for the battery.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a new non-aqueouselectrolyte battery capable of eliminating the problems of the batteriesconventionally proposed as described above.

It is another object of the present invention to provide a non-aqueouselectrolyte battery with increased energy density without deterioratedbattery characteristics.

To achieve these objects, the inventors of the present invention eagerlystudied, and as a result found that the energy density could beincreased without deteriorating the battery characteristics by using amixture of a plurality of kinds of carbonaceous materials whose particlesize distribution areas were controlled and whose average particle sizeswere different as an anode active material of an anode in thenon-aqueous electrolyte battery.

That is, a non-aqueous electrolyte battery according to the presentinvention comprises: a cathode having a cathode active materialcontaining lithium; an anode having an anode active material capable ofbeing doped with/dedoped from lithium; and a non-aqueous electrolyteincluding electrolyte salt. The anode active material is composed of amixture of a plurality of kinds of carbonaceous materials havingdifferent average particle sizes, and when the plurality of kinds ofcarbonaceous materials are arranged in order of small particle size,assuming that the particle size in the order of 10% from the side of asmall particle size is D10, the particle size in the order of 50% fromthe side of a small particle size is D50, and the particle size in theorder of 90% from the side of a small particle size is D90, the anodeactive material has a particle size distribution satisfying relationsrepresented by following expressions 1 and 2.log(D50)−log(D10)≦0.3  (1)(The unit of D is μm and logarithms are respectively common logarithmshaving their bases of 10.)log(D90)−log(D50)≦0.3  (2)(The unit of D is μm and logarithms are respectively common logarithmshaving their bases of 10.)

In this non-aqueous electrolyte battery, the anode active material iscomposed of a mixture of a plurality of kinds of carbonaceous materialshaving different average particle sizes and the particle sizedistribution areas of the plurality of kinds of carbonaceous materialsare narrowed as shown in the above-described expressions 1 and 2. Inthis non-aqueous electrolyte battery, the particle size distribution ofthe anode active material is narrow, and unevenness in performance canbe reduced, depending on the particle size of the anode activematerials.

In this non-aqueous electrolyte battery, since the carbonaceous materialwith a large particle size, among the plurality of kinds of carbonaceousmaterials having different average particle sizes in the anode activematerial, has a small surface area relative to volume, the carbonaceousmaterial decreases its reactivity with the non-aqueous electrolyte tosuppress the decrease of the battery capacity.

Further, in this non-aqueous electrolyte battery, the carbonaceousmaterial of the large particle size forms clearances with suitable sizesin the anode to retain the non-aqueous electrolyte.

In the non-aqueous electrolyte battery, the clearances generated due tothe contact of two or more carbonaceous materials of the large particlesize are efficiently filled with the carbonaceous material of smallparticle sizes among the plurality of kinds of carbonaceous materialshaving the different average particle sizes in the anode activematerials while the carbonaceous material with the small particle sizeleaves in the clearances spaces in which a suitable amount ofnon-aqueous electrolyte can be retained.

In this non-aqueous electrolyte battery, the carbonaceous material ofthe small particle size has a large surface area relative to volumewhich increases its reactivity. Since the amount used of thecarbonaceous material of the small particle size is such an amount as tofill the clearances therewith, the volume density of the anode isimproved to increase the battery capacity as a whole of the anode.

Further, a non-aqueous electrolyte battery according to the presentinvention comprises: a cathode having a cathode active materialcontaining lithium; an anode having an anode active material capable ofbeing doped with/dedoped from lithium; and a non-aqueous electrolyteincluding electrolyte salt. The anode active material is composed of amixture at least including graphite of large particle size whose averageparticle size is located within a range of 20 μm or larger and 40 μm orsmaller and graphite of small particle size whose average particle sizeis located within a range of 5 μm or larger and 16 μm or smaller. Theaverage particle size of the graphite of small particle size is 0.55times the average particle size of the graphite of large particle size,or smaller.

In this non-aqueous electrolyte battery, the anode active material iscomposed of a mixture of a plurality of kinds of graphite havingdifferent average particle sizes such as graphite of large particle sizewhose average particle size is located within a range of 20 μm or largerand 40 μm or smaller and graphite of small particle size whose averageparticle size is located within a range of 5 μm or larger and 16 μm orsmaller. The average particle size of the graphite of small particlesize is 0.55 times the average particle size of the graphite of largeparticle size, or smaller.

Accordingly, in this non-aqueous electrolyte battery, the anode activematerial is composed of a mixture of a plurality of kinds of graphitewhose average particle sizes are located within prescribed ranges.Further, the surface area of the graphite of large particle sizerelative to the volume of the anode is decreased, which decreases itsreaction with the non-aqueous electrolyte. Thus, the decrease in thecapacity of a battery is suppressed.

In the non-aqueous electrolyte battery, the graphite of large particlesize in the anode active material forms clearances of suitable size inthe anode to retain the non-aqueous electrolyte. Accordingly, the ionicresistance to the non-aqueous electrolyte in the anode side is loweredto prevent the deterioration of the battery characteristics.

Further, in the non-aqueous electrolyte battery, when the graphite oflarge particle size in the anode active material is spherical graphite,the spherical graphite of large particle size increases its volumerelative to a surface area. Thus, the central part, which is called thebulk part, except the surfaces on which crystallization is advanced, islarger than that of the graphite of small particle size so that thelithium storage can be increased to increase the capacity of thebattery.

On the other hand, in the non-aqueous electrolyte battery, theclearances in the anode are efficiently filled with the graphite ofsmall particle size in the anode active material while leaving spacescapable of retaining a suitable amount of non-aqueous electrolyte.Therefore, the volume density of the anode can be improved and thecapacity of the battery can be increased to improve energy density.

Still other objects of the present invention and specific advantagesobtained by the present invention will become more apparent from theexplanation of the following embodiments described below.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view showing the inner structure of a lithium-ionsecondary battery according to the present invention.

FIG. 2 is a photograph substituted for a drawing showing enlarged MCMBsas anode active materials used in the lithium-ion secondary batteryaccording to the present invention.

FIG. 3 is a photograph substituted for a drawing showing, as an anodeactive material, crushed artificial graphite in an enlarged stateobtained from a bulk mesophase before a spherical process is appliedthereto.

FIG. 4 is a photograph substituted for a drawing showing, as an anodeactive material, flake natural graphite in an enlarged state to whichthe spherical process is applied to form spherical particles.

FIG. 5 is an explanatory view for explaining a manufacturing step of thelithium-ion secondary battery according to the present invention and aperspective view showing an anode.

FIG. 6 is an explanatory view for explaining a manufacturing step of thelithium-ion secondary battery according to the present invention and aperspective view showing a cathode.

FIG. 7 is an explanatory view for explaining a manufacturing step of thelithium-ion secondary battery according to the present invention and aperspective view showing a battery element.

FIG. 8 is an explanatory view for explaining a manufacturing step of thelithium-ion secondary battery according to the present invention and anexploded perspective view showing that the battery element isaccommodated in an outer package can.

FIG. 9A is a see-through view seeing through and showing a part of theinner structure of the lithium-ion secondary battery, and FIG. 9B is asectional view thereof.

FIG. 10 is an explanatory view for explaining a manufacturing step ofthe lithium-ion secondary battery according to the present invention anda perspective view showing the battery element.

FIG. 11 is an explanatory view for explaining a manufacturing step ofthe lithium-ion secondary battery according to the present invention anda perspective view showing a state that the battery element isaccommodated in an outer package material.

FIG. 12 is an explanatory view for explaining a manufacturing step ofthe lithium-ion secondary battery according to the present invention anda perspective view showing the completed lithium-ion secondary battery.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, a non-aqueous electrolyte battery to which the present invention isapplied will be described below. As a non-aqueous electrolyte battery,one structural example of a lithium-ion secondary battery (referred tohereinafter as a battery) is shown in FIG. 1. In FIG. 1, the battery 1includes a battery element 2 serving as a power generating element, anouter package can 3 for accommodating the battery element 2, non-aqueouselectrolyte solution 4, and a sealing cover body 5.

The battery element 2 has a structure in which an elongated anode 6 andan elongated cathode 7 are spirally coiled in a flat shape with anelongated separator 8 interposed between the anode and the cathode. Ananode current collector 9 of the anode 6 is exposed in an outermostperiphery. In the battery element 2, the anode current collector 9 isexposed in the outermost periphery so that the anode current collector 9comes into electrical contact with the battery can 3. Accordingly, tosimplify the manufacture of the battery, a terminal, a lead, or thelike, for collecting electric current, does not need to be attached tothe anode 6. On the other hand, in the battery element 2, a cathodeterminal 10, electrically connected to the sealing cover body 5, isattached to the cathode 7. The cathode terminal 10 protrudes from oneend face in the direction of width of the separator 8.

The anode 6 has a structure in which an anode composite mixture,including an anode active material and a binding agent, is applied tothe anode current collector 9, dried, and pressed to form an anodecomposite mixture layer 11 on the anode current collector 9.

As the anode active material, for instance, artificial graphite,especially, MCMB (mesophase carbon microbeads), or the like, isemployed. FIG. 2 shows a microphotograph of the MCMB in an enlargedstate.

Then, the MCMB as the artificial graphite is manufactured in thefollowing manner. When the MCMB is produced as the artificial graphite,for instance, coal tar, petroleum pitch, coal pitch, coal tar pitch,mesophase pitch obtained by polymerizing polycyclic aromatichydrocarbon, and distilled pitch, such as a mixture of condensedpolycyclic aromatic hydrocarbon obtained by distilling coal tar, arefirst used as starting materials, and one or a plurality of thesestarting materials are heated at 400° C. to 500° C. In accordance withthis process, the hexagonal ring of carbon is developed in the liquid ofthe starting materials to produce a spherical body having regularity inthe arrangement of carbon atoms such as a crystal, that is, a mesophase.

Then, the starting materials including the mesophase are processed by asolvent such as tar middle oil. Thus, the mesophase is not dissolved inthe solvent because the mesophase is progressively crystallized, andonly parts in which crystallization is not advanced are dissolved in thesolvent and removed. Accordingly, small spherical bodies are obtained.In the mesophase, small spherical bodies, obtained as described above,and particle size or particle size distribution can be controlled byadjusting the temperature of a heating process, time, or the like.

Then, the mesophase small spherical bodies are temporarily burnt at 400°C. to 1200° C., and then, graphitized at 2500° C. to 3200° C. in vacuumor an inert gas atmosphere. In such a way, the MCMBs of artificialgraphite are produced.

In the MCMBs produced in such a manner, crystallization is entirelyadvanced as graphite, however, the degree of crystallization on asurface part is low. In the MCMBs, the surface part, that is, the partin which the degree of crystallization is low has a small amount oflithium storage. However, this part is low in its reactivity with thenon-aqueous electrolyte solution 4, so that a side reaction which causesthe capacity of a battery to be decreased more than the part in whichthe degree of crystallization is high is hardly generated. On the otherhand, in the inner part except the surface, what is called the bulkpart, since crystallization is advanced and the degree ofcrystallization becomes high, the amount of lithium storage is increasedso that the capacity of the battery can be improved.

As the anode active material, spherical carbonaceous materials may beused as well as the MCMBs obtained as described above. Specifically, forinstance, crushed artificial graphite obtained from bulk mesophase orthe like, flake natural graphite, hard carbon such as non-graphitizablecarbon as non-graphite, etc. may be exemplified. These materials areprocessed to be spherical and spherical particles are used. Here, FIG. 3shows a microphotograph in which crushed artificial graphite, obtainedfrom bulk mesophase or the like, is enlarged. FIG. 4 shows amicrophotograph in which flake natural graphite, formed in sphericalparticles under a process for making the spherical particles, isenlarged.

The spherical carbonaceous materials are different from the MCMBs. Mostof the spherical materials usually have no difference in materialitybetween their surfaces and inner parts. However, for instance, a surfacetreatment is applied to the surfaces of the spherical carbonaceousmaterials so that the surfaces are amorphous. Thus, the materiality ofthe surfaces can be controlled. In the spherical carbonaceous materials,the filling characteristic of the anode composite mixture layer 11 canbe improved due to spherical forms. Further, in the sphericalcarbonaceous materials, since the surface treatment is performed so thatthe surfaces are amorphous, the reaction with the non-aqueouselectrolyte solution 4 on the surfaces can be suppressed.

Then, when the spherical carbonaceous materials to which theabove-described spherical process or the surface treatment is appliedare used as the anode active material, the mixture of a plurality ofkinds of spherical carbonaceous materials different in their averageparticle size is employed where the plurality of spherical carbonaceousmaterials have a particle size distribution satisfying the relationshiprepresented by below-described expressions 3 and 4. For both expressions3 and 4, D10, D50, and D90 represent components of a particle sizedistribution, which can be measured by, for example, using a laserdiffraction method. Within the particle size distribution, D10represents a particle size such that 10% of the particles in thecarbonaceous material mixture are smaller than D10, D50 represents aparticle size such that 50% of the particles in the carbonaceousmaterial mixture are smaller than D50, and D90 represents a particlesize such that 90% of the particles in the carbonaceous material mixtureare smaller than D90.log(D50)−log(D10)≦0.3  (3)(The unit of D is μm and logarithms are respectively common logarithmshaving their bases of 10.)log(D90)−log(D50)≦0.3  (4)(The unit of D is μm and logarithms are respectively common logarithmshaving their bases of 10.)

Thus, in the anode active material, the spherical carbonaceous materialsof large particle size of the spherical carbonaceous materials havingdifferent average particle sizes have a surface area relatively smallerthan that of the spherical carbonaceous materials of small particlesize. Accordingly, the spherical carbonaceous materials of largeparticle size decrease a reaction with the non-aqueous electrolytesolution 4 to suppress the decrease of the capacity of a battery.Further, the spherical carbonaceous materials of large particle sizehave large volume relative to surface area. Therefore, the central part,except the surface in which crystallization is advanced, what is calleda bulk part has a volume larger than that of the spherical carbonaceousmaterials of small particle size to increase the capacity of thebattery. Further, the spherical carbonaceous materials of large particlesize form clearances of suitable size in the anode composite mixturelayer 11 so as to retain the non-aqueous electrolyte solution 4. On theother hand, the clearances in the anode composite mixture layer 11 areefficiently filled with the spherical carbonaceous materials of smallparticle size of the spherical carbonaceous materials having differentaverage particle sizes. At this time, the spherical carbonaceousmaterials of small particle size leave spaces in which suitable amountof non-aqueous electrolyte solution 4 can be retained.

Accordingly, in the anode active material, the mixture of a plurality ofkinds of spherical carbonaceous materials whose particle sizedistribution areas are controlled to be narrow and whose averageparticle sizes are different is used. Thus, the clearances that theelectrolyte in a composite mixture application film of the anode 6enters are made optimum so that desired electrolyte is retained withoutlowering volume density. Further, the high ionic conductivity of theelectrolyte in the anode composite mixture application film is ensuredto prevent the deterioration of battery characteristics and the volumedensity of the anode composite mixture layer 11, that is, fillingdensity is improved to increase the capacity of the battery.

In the anode active material, the spherical carbonaceous material can bedivided into the surface part in which crystalline characteristics arelow like the MCMB and the bulk part except the surface part in whichcrystalline characteristics are high by performing the above-describedsurface treatment or the like. In the above-described sphericalcarbonaceous material, the surface part in which the crystallinecharacteristics are low decreases a capacity in view of batterycharacteristics, what is called an amount of lithium storage, however,decreases a reactivity with the non-aqueous electrolyte solution 4. Onthe other hand, the bulk part in which the crystalline characteristicsare high increases a reactivity with the non-aqueous electrolytesolution 4, however, increases an amount of lithium storage. That is, inthe spherical carbonaceous material, the bulk part substantiallyoccupies most of the volume and has the high crystallinecharacteristics, so that the bulk part has the large amount of lithiumstorage and the high reactivity with the non-aqueous electrolytesolution 4. However, since the crystalline characteristics of thesurface that mainly comes into contact with the non-aqueous electrolytesolution 4 are low, a reaction with the non-aqueous electrolyte solution4 is suppressed.

Further, in the anode active material, when the particle sizedistribution areas of the spherical carbonaceous material of the largeparticle size and the spherical carbonaceous material of the smallparticle size extend, two or more spherical carbonaceous materials ofthe large particle size come into contact with each other. Thus,clearances of various sizes are formed. In this case, when theclearances are to be filled with the spherical carbonaceous materials ofthe small particle size, the spherical carbonaceous materials may notenter the clearances, because they are too large. Otherwise, theclearances may be too tightly filled with the spherical carbonaceousmaterials of the small particle size because they are too small. Finepowder in the spherical carbonaceous materials of the small particlesize especially decreases the capacity and especially increases thereactivity with the non-aqueous electrolyte solution 4. Consequently,the capacity of the battery is decreased so that the capacity isseriously decreased and the safety is lowered. Accordingly, in the anodeactive material, the particle size distribution areas of the sphericalcarbonaceous materials having different average particle sizes arenarrowed, which is important an condition in obtaining good batterycharacteristics.

Further, when spherical graphite such as the MCMB is used as the anodeactive material, graphite of large particle size whose average particlesize is located within a range of 20 μm or larger and 40 μm or smalleris mixed with graphite of small particle size whose average particlesize is located within a range of 5 μm or larger and 16 μm or smallerand the average particle size of the graphite of small particle size is0.55 times the average particle size of the graphite of large particlesize, or smaller. That is, as the anode active material, the mixture ofa plurality of kinds of spherical graphite in which the particle sizedistributions are controlled to be narrow and the average particle sizesare different is employed.

Specifically, the distribution of the graphite of large particle size isset forth by the following expressions 5 and 6, where DL10, DL50, andDL90 represent components of a particle size distribution for thegraphite of large particle size. Within the particle size distribution,DL10 represents a graphite particle size such that 10% of the largeparticle graphite is smaller than DL10, DL50 represents a graphiteparticle size such that 50% of the large particle graphite is smallerthan DL50, and DL90 represents a graphite particle size such that 90% ofthe large particle graphite is smaller than DL90.log(DL50)−log(DL10)≦0.22  (5)(The unit of DL is μm and logarithms are respectively common logarithmshaving their bases of 10.)log(DL90)−log(DL50)≦0.22  (6)(The unit of DL is μm and logarithms are respectively common logarithmshaving their bases of 10.)

Thus, the graphite of large particle size of the spherical graphitehaving different average particle sizes has its surface area relativelysmaller than that of the graphite of small particle size so that thegraphite of large particle size decreases a reaction with thenon-aqueous electrolyte solution 4 and suppresses the decrease of thecapacity of the battery. Further, since the graphite of large particlesize has a large volume relative to a surface area, a bulk part has alarge volume relative to the graphite of small particle size to increasethe capacity of a battery. Further, the graphite of large particle sizeforms clearances of appropriate size in the anode composite mixturelayer 11 to retain the non-aqueous electrolyte solution 4 therein.

On the other hand, the distribution of for the graphite of smallparticle size is set forth by the following expressions 7 and 8, whereDS10, DS50, and DS90 represent components of a particle sizedistribution for the graphite of small particle size. Within thisparticle size distribution, DS10 represents a graphite particle sizesuch that 10% of the small particle graphite is smaller than DS10, DS50represents a graphite particle size such that 50% of the small particlegraphite is smaller than DS50, and DS90 represents a graphite particlesize such that 90% of the small particle graphite is smaller than DS90.log(DS50)−log(DS10)≦0.22  (7)(The unit of DS is μm and logarithms are respectively common logarithmshaving their bases of 10.)log(DS90)−log(DS50)≦0.22  (8)(The unit of DS is μm and logarithms are respectively common logarithmshaving their bases of 10.)

Thus, the clearances in the anode composite mixture layer 11 areefficiently filled with graphite of small particle size of the sphericalgraphite having different average particle sizes while spaces are leftunfilled in which a suitable amount of the non-aqueous electrolytesolution 4 can be retained.

Accordingly, in the anode active material, the mixture of a plurality ofkinds of spherical graphite, whose particle size distribution areas arecontrolled to be narrow and whose average particle sizes are different,is used. Thus, ionic resistance to the non-aqueous electrolyte solution4 in the anode 6 side is lowered to prevent the deterioration of batterycharacteristics, and the volume density of the anode composite mixturelayer 11, that is, filling density is improved to increase the capacityof the battery.

In the anode active material, the spherical graphite, especially, theMCMB can be divided into the surface part in which crystallinecharacteristics are low and the bulk part except the surface part inwhich crystalline characteristics are high, as described above. In theMCMB, the surface part in which the crystalline characteristics are lowdecreases an amount of lithium storage, however, decreases a reactivitywith the non-aqueous electrolyte solution 4. On the other hand, the bulkpart in which the crystalline characteristics are high increases areactivity with the non-aqueous electrolyte solution 4, however,increases an amount of lithium storage. That is, also in the sphericalgraphite, the bulk part substantially occupies most of the volume andhas the high crystalline characteristics so that the bulk part has thelarge amount of lithium storage and the high reactivity with thenon-aqueous electrolyte solution 4. However, since the crystallinecharacteristics of the surface that mainly comes into contact with thenon-aqueous electrolyte solution 4 are low, a reaction with thenon-aqueous electrolyte solution 4 is suppressed.

Further, in the anode active material, when the particle sizedistribution areas of the spherical graphite of the large particle sizeand the spherical graphite of the small particle size extend, two ormore spherical graphite of the large particle size come into contactwith each other. Thus, clearances of various sizes are formed. In thiscase, when the clearances are to be filled with the spherical graphiteof the small particle size, the spherical graphite may not enter theclearances because they are too large. Otherwise, the clearances may betoo tightly filled with the spherical graphite of the small particlesize because they are too small. Fine powder in the spherical graphiteof the small particle size especially decreases a capacity andespecially increases the reactivity with the non-aqueous electrolytesolution 4. Consequently, the capacity of the battery is decreased sothat the capacity is seriously decreased and the safety is lowered.Accordingly, in the anode active material, the particle sizedistribution areas of the spherical graphite having different averageparticle sizes are narrowed, which is important condition in obtaininggood battery characteristics.

In the anode active material, when the average particle size of thegraphite of large particle size is smaller than 20 μm, the particle sizeof the graphite of large particle size is too small and substantiallyhas no difference from the range of the average particle size of thegraphite of small particle size. Consequently, the anode compositemixture layer 11 is filled with the spherical graphite withoutclearances. Thus, pressure is excessively exerted on the sphericalgraphite under compression molding when the anode 6 is manufactured sothat the surfaces of the particles of the spherical graphite are brokento deteriorate the battery characteristics. Further, since the surfacearea is relatively increased, reactivity with the electrolyte isincreased to decrease the capacity of the battery. On the other hand, inthe anode active material, when the average particle size of thegraphite of large particle size is larger than 40 μm, the particle sizeis too large. Thus, the volume density of the anode composite mixturelayer 11 is hardly improved under compression molding when the anode 6is manufactured. Since cracks are generated in the particles due to thecompression molding, the battery characteristics are deteriorated.

Accordingly, in the anode active material, the average particle size ofthe graphite of large particle size is located within a range of 20 μmor larger and 40 μm or smaller. Thus, the particles do not crack underthe compression molding or the like upon manufacturing the anode 6 andthe deterioration of the battery characteristics is suppressed.

In the anode active material, when the average particle size of thegraphite of small particle size is smaller than 5 μm, the particle sizeof the graphite of small particle size is too small. Thus, not only theclearances in the anode composite mixture layer 11, but also the spacesin which the non-aqueous electrolyte solution 4 is retained are filledwith the graphite of small particle size to decrease an electric contactbetween the anode 6 and the non-aqueous electrolyte solution 4.Accordingly, the battery characteristics are deteriorated. In this case,since the surface area of the spherical graphite is too large so as toincreases the reactivity with the non-aqueous electrolyte solution 4,the safety of the battery is deteriorated. On the other hand, in theanode active material, when the average particle size of the graphite ofsmall particle size is larger than 16 μm, the particle size of graphiteof small particle size is too large. The particle size of the graphiteof small particle size substantially has no difference from the range ofthe average particle size of the graphite of large particle size.Accordingly, clearances in the composite mixture layer 11 that areformed by allowing two or more graphite of large particle size to comeinto contact with each other are hardly efficiently filled with thegraphite of small particle size. Thus, the volume density of the anodecomposite mixture layer 11 is decreased and energy density can not beimproved.

Accordingly, in the anode active material, the average particle size ofthe graphite of small particle size is located within a range of 5 μm orlarger and 16 μm or smaller. Thus, the clearances in the anode compositemixture layer 11 are efficiently filled with the graphite of smallparticle size, while spaces in which a suitable amount of non-aqueouselectrolyte solution 4 can be retained are left unfilled. Thus, theenergy density is improved.

Further, in the anode active material, when the average particle size ofthe graphite of small particle size is larger than 0.55 times theaverage particle size of the graphite of large particle size or smaller,there is no difference in average particle size between the graphite oflarge particle size and the graphite of small particle size. Further,the clearances in the anode composite mixture layer 11 that are produceddue to the contact of two or more graphite of large particle size arehardly efficiently filled with the graphite of small particle size.Thus, the volume density of the anode composite mixture layer 11 isreduced. In this case, when the clearances are formed in the anodecomposite mixture layer 11, the clearances in the anode compositemixture layer 11 become large while charging and discharging operationsare repeated. Thus, the contact of the spherical graphite is separate toincrease an ionic resistance to the non-aqueous electrolyte solution 4of the anode 6 side and deteriorate the battery characteristics.Further, when there is no difference in average particle size betweenthe graphite of small particle size and the graphite of large particlesize, pressure is excessively exerted on the spherical graphite undercompression molding when the anode 6 is produced to crack the sphericalgraphite. Accordingly, the battery characteristics are deteriorated.

Therefore, in the anode active material, the average particle size ofthe graphite of small particle size is not larger than 0.55 times theaverage particle size of the graphite of large particle size, orsmaller. Thus, the graphite of small particle size has an appropriatesize relative to the graphite of large particle size. Accordingly, theabove-described operational effect of the graphite of large particlesize and the operational effect of the graphite of small particle sizecan be obtained.

Further, in the anode active material, when the spherical graphite isused, the graphite of large particle size is mixed with the graphite ofsmall particle size in the weight ratio ranging from 65:35 to 90:10. Forthe anode active material, when the mixture of the graphite of largeparticle size and the graphite of small particle size is used and thegraphite of large particle size is mixed in a weight ratio lower than65% relative to all the spherical graphite, the graphite of smallparticle size having a larger surface area and a high reactivity withthe non-aqueous electrolyte solution 4 is too much, so that the safetyis lowered. Further, since the surface area is large and the reactivitywith the electrolyte is high, the capacity of the battery is reduced.Further, in this case, since the graphite of small particle size is toomuch, even the spaces in which the non-aqueous electrolyte solution 4 inthe anode composite mixture layer 11 is retained are filled with thegraphite of small particle size. Accordingly, an amount of thenon-aqueous electrolyte solution 4 with which the anode compositemixture layer 11 is impregnated is decreased. Thus, an ionic resistanceto the non-aqueous electrolyte solution 4 of the anode 6 side isincreased to deteriorate the battery characteristics. On the other hand,when the mixture of graphite of large particle size and graphite ofsmall particle size is used as the anode active material and thegraphite of large particle size is mixed in a weight ratio higher than90% relative to all the spherical graphite, the amount of the graphiteof small particle size is too small. Consequently, the clearances in theanode composite mixture layer 11 cannot be efficiently filled with thegraphite of small particle size. Thus, the volume density of the anodecomposite mixture layer 11 is hardly increased to increase the capacityof the battery.

In the anode 6, as a binding agent of the anode composite mixture layer11, binding agents such as polyvinylidene fluoride or styrene butadienerubber, used as an anode composite mixture of a non-aqueous electrolytebattery, may be used. In addition, a well-known additive agent or thelike may be added to the anode composite mixture layer 11. In the anode6, as the anode current collector 9, a foil type metal made of, forinstance, copper or a net shaped metal or the like is employed.

The cathode 7 has a structure such that a cathode composite mixturelayer 13 is formed on a cathode current collector 12 by applying, dryingand pressing cathode composite mixture including a cathode activematerial and a binding agent on the cathode current collector 12. In thecathode 7, the cathode terminal 10 is connected to a prescribed positionof the cathode current collector 12 so as to protrude in the directionof width of the cathode current collector 12. As the cathode terminal10, an elongated metal piece made of, for instance, aluminum is used.

As the cathode active material, lithium composite oxide, represented byLiM_(x)O₂, (where, M indicates one or more kinds of transition metalsincluding Co, Ni, Mn, Fe, Al, V, Ti, etc., x depends on the charging anddischarging states of a battery and is ordinarily greater than or equalto 0.05 or less than or equal to 1.10, or the like is employed. As thetransition metals M forming the lithium composite oxide, Co, Ni, Mn orthe like is preferable. As specific examples of the lithium compositeoxide, LiCoO₂, LiNiO₂, LiNi_(y)Co_(1-y)O₂ (where the range of y isrepresented by 0<y<1.), LiMn₂O₄, etc. may be exemplified. Further, asthe cathode active materials, compounds represented by, for instance,Li_(x)Fe_(1-y)M_(y)PO₄ (where M indicates any one or more kinds of Mn,Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B and Nb, x is located withina range represented by 0.05≦x≦1.2, and y is located within a rangerepresented by 0≦y≦0.8) may be exemplified. Specifically, LiFePO₄ or thelike is employed. As the cathode active material, for instance, metalsulfides or oxides such as TiS₂, MoS₂, NbSe₂, V₂O₅, etc. may beemployed.

In the cathode 7, as the binding agent of the cathode composite mixturelayer 13, binding agents such as polyvinylidene fluoride,tetrafluoroethylene, etc. used in a cathode composite mixture of anon-aqueous electrolyte battery can be used. In addition, for instance,a carbonaceous material may be added to the cathode composite mixturelayer 13 as a conductive material, or a well-known additive agent or thelike may be added thereto. In the cathode 7, as the cathode currentcollector 12, for instance, foil type metal or net type metal made ofaluminum is used.

In the battery element 2, the separator 8 serves to separate the anode 6from the cathode 7 and a well-known material ordinarily used as aninsulating porous film of this kind of non-aqueous electrolyte batterymay be used. Specifically, a polymer film such as polypropylene,polyethylene, etc, is used. Further, the separator 8 is preferably thinas much as possible from the viewpoint of the relation between lithiumion conductivity and energy density. The separator, with the thicknessof 30 μm or smaller, is used.

The outer package can 3 is a tubular vessel having, for instance, arectangular or a flat circular bottom surface and has such a dimensionso as to insert the battery element 2 in a direction substantiallyparallel to the direction of width of the separator 8. When the outerpackage can 3 is electrically connected to the anode current collector 9of the anode 6 due to contact, the outer package can 3 is made of, forinstance, iron, stainless steel, nickel, etc. When the outer package can3 is electrically connected to the cathode current collector 12 of thecathode 7, the can is made of aluminum. When the outer package can 3 ismade of, for instance, iron, the surface thereof is plated with nickel.

The non-aqueous electrolyte solution 4 is prepared by dissolvingelectrolyte salt in a non-aqueous solvent. As the non-aqueous solvent, asolvent having a relatively high dielectric constant is used.Specifically, cyclic carbonates such as propylene carbonate, ethylenecarbonate, etc., chain carbonates such as diethyl carbonate, dimethylcarbonate, etc., solvents obtained by replacing hydrogens of thesecarbonates by halogens, carboxylic esters such as methyl propionate,methyl butyrate, etc., ethers such as 2-methyl tetrahydrofuran,dimethoxyethane, butyrolactones such as γ-butyrolactone, valerolactonessuch as γ-valerolactone, sulfolanes, etc. may be exemplified. Then, amixture of one or more kinds of these non-aqueous solvents is used.

For instance, when the above-described graphite is employed as the anodeactive material, ethylene carbonate or ethylene carbonate in whichhydrogen atoms are replaced by halogen elements or the like are employedas main solvents of the non-aqueous solvent. To these main solvents, forinstance, propylene carbonate, butylene carbonate, 1,2-dimethoxyethane,γ-butyrolactone, valerolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, sulfolane,methyl sulfolane, etc. are added as a second solvent component within arange less than 10 vol %.

As electrolyte salt used in the non-aqueous solution 4, electrolyte saltordinarily employed in the electrolyte solution of the non-aqueouselectrolyte battery can be used. Specifically, LiPF₆, LiBF₄, LiAsF₆,LiClO₄, LiB(C₆H₅)₄, CH₃SO₃Li, CF₃SO₃Li, LiN(SO₂CF₃)₂, LiN(SO₂C₂F₅)₂,LiC(SO₂CF₃)₃, LiAlCl₄, LiSiF₆, LiCl, LiBr, etc. may be enumerated. Amixture of one or a plurality of kinds of these electrolyte salts isused. Especially, as the electrolyte, LiPF₆ and LiBF₄, excellent inoxidation stability, are employed. The concentration of the electrolytesalt relative to the non-aqueous solvent is not especially limited.However, it is set to a range of 0.4 mole/liter or more and 1.5mole/liter or less. The above-described concentration-range makes itpossible to raise the ionic conductivity of the non-aqueous solution 4.

The sealing cover body 5 has a structure that a terminal part 15 isfitted to a substantially central part of a sealing plate material 14through an insulating gasket 16. The sealing plate material 14 is madeof, for instance, iron, stainless steel, nickel, etc. when the outerpackage can 3 is electrically connected to the anode 6. Especially, whenthe sealing plate material 14 is formed with iron, the surface of thesealing plate material is plated with nickel. When the cathode terminal10 is connected to the terminal part 15, the terminal part 15 is madeof, for instance, aluminum or the like. For the insulating gasket 16, aninsulating resin such as polypropylene is used. The insulating gasket 16may be formed with a hermetic seal such as glass.

The battery 1 having the above-described structure is manufactured asdescribed below. First, the anode 6 is manufactured. When the anode 6 ismanufactured, as shown in FIG. 5, an anode composite mixture, whichincludes the anode active material composed of a mixture of a pluralityof kinds of spherical graphite having different average particle sizesand a binding agent, is prepared. This anode composite mixture isuniformly applied to the anode current collector 9 made of, forinstance, a copper foil, so as to provide a part 6 a to which the anodecomposite mixture is not applied and dried to form the anode compositemixture layer 11. The anode current collector having the anode compositemixture layer is cut to a prescribed dimension. In such a manner, theelongated anode 6 is manufactured.

Then, the cathode 7 is manufactured. When the cathode 7 is manufactured,as shown in FIG. 6, cathode composite mixture, including the cathodeactive material and a binding agent, is prepared. This cathode compositemixture is uniformly applied and dried on the cathode current collector12 made of, for instance, aluminum, so as to provide a part 7 a to whichthe cathode composite mixture is not applied to form a cathode compositemixture layer 13. The cathode current collector having the cathodecomposite mixture layer is cut to a prescribed dimension. Then, thecathode terminal 10 is connected to the part 7 a of the cathode currentcollector 12 to which the cathode composite mixture is not applied by anultrasonic welding method or a spot welding method or the like. In sucha manner, the elongated cathode 7 is manufactured.

Subsequently, as shown in FIG. 7, the anode 6 and the cathode 7,obtained as described above, are laminated through the elongatedseparators 8, and the laminated body is spirally coiled many times in aflat shape to form the battery element 2. At this time, the batteryelement 2 is spirally coiled in such a way that the anode currentcollector 9 is exposed in an outermost periphery and the cathodeterminal 10 protrudes from one end face in the direction of width of theseparator 8.

Then, as shown in FIG. 8, an insulating plate 17 a is inserted into abottom part of the thin and rectangular outer package can 3 made of ironand having a surface plated with nickel. Further, while an insulatingplate 17 b is mounted on the end face of the battery element 2 in theside where the cathode terminal 10 protrudes, the battery element 2 isaccommodated in the outer package can 3 so that the cathode terminal 10faces the opening side of the outer package can 3. Then, the end part ofthe cathode terminal 10 is connected to the terminal part 15 of thesealing cover body 5.

After that, the non-aqueous electrolyte solution 4 is injected into theouter package can 3 in which the battery element 2 is accommodated.Then, the opening edge part of the outer package can 3 and theperipheral edge part of the sealing plate material 14 of the sealingcover body 5 are welded and sealed without spaces by, for instance, alaser welding method. Thus, the outer package can 3 and the sealingplate material 14 are electrically conducted to the anode 6 to serve asan external anode of the battery 1. Further, the terminal part 15 iselectrically conducted to the cathode 7 to serve as an external cathodeof the battery 1. In this manner, the thin battery 1 is manufactured.

In the battery 1, manufactured as described above, when, for instance,the spherical graphite is used for the anode active material, themixture composed of a plurality of kinds of spherical graphite havingdifferent average particle sizes, whose particle size distribution areais controlled to be narrow as the anode active material is employed.Thus, the spherical graphite having a large particle size among thespherical graphite having different average particle sizes relativelydecreases the surface area more than the spherical graphite having asmall particle size. Accordingly, a reaction with the non-aqueouselectrolyte solution 4 is decreased to suppress the decrease of thecapacity of the battery.

Further, in this battery 1, since the spherical graphite having thelarge particle size increases the volume relative to the surface area,the bulk part becomes large relative to the spherical graphite havingthe small particle to increase the capacity of the battery.

Further, in this battery 1, the spherical graphite having the largeparticle size forms clearances of adequate sizes in the anode compositemixture layer 11 to retain the non-aqueous electrolyte solution 4 anddecrease an ionic resistance to the non-aqueous electrolyte solution 4in the anode 6 side. Thus, the deterioration of battery characteristicscan be prevented.

Still further, in this battery 1, the clearances in the anode compositemixture layer 11 are efficiently filled with the spherical graphitehaving the small particle size among the spherical graphite havingdifferent average particle sizes while the spherical graphite having thesmall particle size leaves spaces in which a suitable amount ofnon-aqueous electrolyte solution 4 can be retained. Accordingly, thevolume density of the anode composite mixture layer 11 is enhanced toincrease the capacity of the battery and improve energy density.

In the above-described embodiment of the present invention, the battery1, using the non-aqueous electrolyte solution 4 obtained by dissolvingthe electrolyte salt in the non-aqueous solvent, is described as anexample. However, the present invention is not limited thereto. As shownin FIGS. 9A and 9B, the present invention may be applied to a solidelectrolyte battery (referred to hereinafter as a battery) 20 using nonon-aqueous electrolyte solution 4. In the battery 20, parts common tothe above-described battery 1 are designated by the same referencenumerals and a detailed description thereof will be omitted.

In the battery 20, a polymer electrolyte 21 such as a solid polymerelectrolyte having electrolyte salt contained in an organic polymer or agel electrolyte having a polymer matrix impregnated with electrolytesalt and a non-aqueous solvent is formed on an anode composite mixturelayer 11 of an elongated anode 6 and a cathode composite mixture layer13 of an elongated cathode 7. While a separator 8 is provided betweenthe anode 6 and the cathode 7, the anode and the cathode are spirallycoiled to form a battery element 22 serving as a power generationelement. This battery element 22 is sealed in an outer package material23.

The anode 6 has a structure that an anode composite mixture including ananode active material and a binding agent is applied, dried and pressedon an anode current collector 9 to compression-mold an anode compositemixture layer 11 on the anode current collector 9. To the anode 6, ananode terminal 24 is connected to a prescribed position of the anodecurrent collector 9 so as to protrude in the direction of width of theanode current collector 9. As the anode terminal 24, for instance, anelongated metallic piece made of copper, nickel, etc. is used. As theanode active material, the same materials as those of theabove-described battery 1 are employed. In the anode 6, the same bindingagent or the like as that of the above-described battery 1 is includedin the anode composite mixture layer 11. Further, as the anode currentcollector 9, a foil type metal or a net type metal, etc. made of, forinstance, copper is used like the above-described battery 1.

The cathode 7 has the same structure as that of the above-describedbattery 1. As a cathode active material, the same materials as those ofthe above-described battery 1 are employed. In the cathode 7, the samebinding agent and conductive material, etc. as those of theabove-described battery 1 are included in the cathode composite mixturelayer 13. For a cathode current collector 12, a foil type metal or a nettype metal or the like made of, for instance, aluminum is employed likethe above-described battery 1.

As the polymer electrolyte 21, any of a solid inorganic electrolyte anda solid polymer electrolyte having lithium ion conductivity can be used.As the solid inorganic electrolyte, for example, lithium nitride,lithium iodide, etc. may be exemplified. On the other hand, the solidpolymer electrolyte is composed of the above-described electrolyte saltand an organic polymer for dissolving it. As the organic polymer, forinstance, ether polymers such as poly (ethylene oxide) or cross-linkedmaterials thereof may be independently used or copolymerized or mixedwith molecules and the obtained product may be used.

In the case of the gel electrolyte, as the polymer matrix, various kindsof polymers that absorb the above-described non-aqueous electrolytesolution to gel may be employed. For example, polyvinylidene fluoride,polyacrylonitrile, polyethylene oxide, polypropylene oxide,polymethacrylonitrile, etc. may be exemplified. Any one or a mixture ofa plurality of these kinds of materials may be used.

In the outer package material 23, two or more layers of insulatinglayers or metal layers are laminated and stuck together by a laminateprocess so that an inner surface of a battery is made of an insulatinglayer. For the insulating layers, materials that show adhesivecharacteristics to a cathode terminal 10 or the anode terminal 24 arenot especially limited to specific materials. Materials made ofpolyolefine resin such as polyethylene, polypropylene, modifiedpolyethylene, modified polypropylene and copolymers of them, etc. arecapable of lowering the penetrability and excellent in air-tightness areused. For the metal layers, aluminum, stainless steel, nickel, iron orthe like, formed in a foil shape or a plate shape, is used. Further, aninsulating layer made of, for instance, nylon is laminated on anoutermost layer, so that strength against breakage or piercing can beenhanced.

The battery 20 having such a structure is manufactured as describedbelow. First, the anode 6 is manufactured. When the anode 6 ismanufactured, anode composite mixture, which includes the anode activematerial composed of a mixture of a plurality of kinds of sphericalgraphite having different average particle sizes and a binding agent, isprepared. This anode composite mixture is uniformly applied to the anodecurrent collector 9 made of, for instance, a copper foil, so as toprovide a part 6 a to which the anode composite mixture is not appliedand dried to form the anode composite mixture layer 11. The anodecurrent collector including the anode composite mixture layer is cut toa prescribed dimension. Then, the anode terminal 24 is connected to thepart 6 a of the anode current collector 9 to which the anode compositemixture is not applied by, for instance, an ultrasonic welding method ora spot welding method. In such a manner, the elongated anode 6 ismanufactured.

Then, the cathode 7 is manufactured like the above-described battery 1.When the cathode 7 is manufactured, cathode composite mixture includingthe cathode active material and a binding agent is prepared. Thiscathode composite mixture is uniformly applied and dried on the cathodecurrent collector 12 made of, for instance, aluminum so as to provide apart 7 a to which the cathode composite mixture is not applied to formthe cathode composite mixture layer 13. The cathode current collectorhaving the cathode composite mixture layer is cut to a prescribeddimension. Then, the cathode terminal 10 is connected to the part 7 a ofthe cathode current collector 12 to which the cathode composite mixtureis not applied by an ultrasonic welding method or a spot welding methodor the like. In such a manner, the elongated cathode 7 is manufactured.

Subsequently, the polymer electrolytes 21 are respectively formed inlayers on the main surface of the anode composite mixture layer 11 ofthe anode 6 and on the main surface of the cathode composite mixturelayer 13 of the cathode 7 which are manufactured as described above.When electrolyte layers are formed, non-aqueous electrolyte solution 4is prepared like the above-described battery 1. Then, the non-aqueouselectrolyte solution 4 and an organic polymer are mixed and agitatedwith a non-aqueous solvent as a dilution solvent as desired to preparesol electrolyte solution. This electrolyte solution is appliedrespectively on the main surface of the anode composite mixture layer 11of the anode 6 and the main surface of the cathode composite mixturelayer 13 of the cathode 7 to form electrolyte films. When the dilutionsolvent is used, the non-aqueous solvent thereof is evaporated to form agel electrolyte. In such a manner, the polymer electrolytes 21 arerespectively formed on the anode 6 and the cathode 7.

Then, as shown in FIG. 10, the anode 6 and the cathode 7 having thepolymer electrolytes 21 formed on the main surfaces as described aboveare laminated through a separator 8 so that the electrolyte layers areopposed to each other. The laminated body is spirally coiled in a flatform in the longitudinal direction of the separator 8 to form a batteryelement 22. At this time, the anode terminal 24 and the cathode terminal10 are adapted to protrude from one end face of the battery element 22.

Then, as shown in FIG. 11, while the anode terminal 24 and the cathodeterminal 10 provided in the battery element 22 are drawn out, thebattery element is accommodated in the outer package material 23. Atthis time, the battery element is accommodated in the outer packagematerial 23 in such a way that resin pieces 25 made of propylene havingadhesive characteristics are interposed between the anode terminal 24and the cathode terminal 10, and the outer package material 23. Thus, inthe battery 20, the short-circuit between the anode terminal 24 and thecathode terminal 10 and the metal layer in the outer package material 23or the deterioration of air-tightness or the like is prevented.

Then, as shown in FIG. 12, the peripheral edges of the outer packagematerial 23 in which the battery element 22 is accommodated are stucktogether to seal the battery element 22 in the outer package material23. In such a manner, the battery using the polymer electrolytes 21 isproduced.

In the battery 20 manufactured as described above, the mixture composedof a plurality of kinds of spherical graphite having different averageparticle sizes whose particle size distribution area is controlled to benarrow as the anode active material is employed like the above-describedbattery 1. Thus, the spherical graphite having a large particle sizeamong the spherical graphite having different average particle sizesrelatively decreases the surface area more than the spherical graphitehaving a small particle size. Accordingly, a reaction with the polymerelectrolyte 21 is decreased to suppress the decrease of the capacity ofthe battery.

Further, in this battery 20, since the spherical graphite having thelarge particle size increases a volume relative to the surface area, abulk part becomes large relative to the spherical graphite having thesmall particle size to increase the capacity of the battery.

Further, in this battery 20, the spherical graphite having the largeparticle size forms clearances of adequate sizes in the anode compositemixture layer 11 to retain the polymer electrolyte 21 and decrease anionic resistance to the polymer electrolyte 21 in the anode 6 side.Thus, the deterioration of battery characteristics can be prevented.

Still further, in this battery 20, the clearances in the anode compositemixture layer 11 are efficiently filled with the spherical graphitehaving the small particle size among the spherical graphite havingdifferent average particle sizes while the spherical graphite having thesmall particle size leaves spaces in which a suitable amount of polymerelectrolyte 21 can be retained. Accordingly, the volume density of theanode composite mixture layer 11 is enhanced to increase the capacity ofthe battery and improve energy density.

The form of the non-aqueous electrolyte battery to which the presentinvention is applied is not especially limited to specific forms such asa cylindrical type, a prismatic type, a coin type, a button type, etc.Further, the non-aqueous electrolyte battery may be formed in thinshapes, large shapes or various kinds of sizes. Further, in theabove-described embodiments, the battery element 2 of the battery 1 andthe battery element 22 of the battery 20 are spirally coiled. However,the present invention is not limited thereto. The present invention maybe applied to non-aqueous electrolyte batteries using battery elementshaving structures described below. That is, for instance, a plurality ofanodes and cathodes are laminated in multi-layers through separators, oran elongated anode and an elongated cathode are folded in a zigzagmanner, which is called in a state of bellows through a separator.

In the above-described embodiments, the spherical graphite is used asthe anode active material in the battery 1 and the battery 20, however,the present invention is not limited thereto. For instance, thespherical carbonaceous material that undergoes the above-describedspherical process and the surface treatment is used so that the sameeffects as those of the battery 1 and the battery 20 can be obtained.

EXAMPLES

Now, as non-aqueous electrolyte batteries to which the present inventionis applied, samples that lithium-ion secondary batteries using gelelectrolyte are actually manufactured will be described below.

Sample 1 to Sample 68

Sample 1 to Sample 68 use a mixture of two kinds of MCMBs, which iscalled spherical graphite, having different average particle sizes as ananode active material. These Samples are produced under conditions suchas particle sizes, mixing ratios, etc., of the spherical graphite asshown in Table 1 to Table 3.

TABLE 1 Spherical Graphite 1 Particle Size Distribution D50 D10 D90log(D50) − (μm) (μm) (μm) log(D10) log(D90) − log(D50) Sample 1 20 12.431.7 0.208 0.200 Sample 2 20 12.4 31.7 0.208 0.200 Sample 3 25 16.2 38.60.188 0.189 Sample 4 30 19.3 44.7 0.192 0.173 Sample 5 30 19.3 44.70.192 0.173 Sample 6 30 19.3 44.7 0.192 0.173 Sample 7 30 19.3 44.70.192 0.173 Sample 8 30 19.3 44.7 0.192 0.173 Sample 9 30 19.3 44.70.192 0.173 Sample 10 35 23.2 52.4 0.179 0.175 Sample 11 40 26.3 61.20.182 0.185 Sample 12 40 26.3 61.2 0.182 0.185 Sample 13 40 26.3 61.20.182 0.185 Sample 14 30 18.1 49.7 0.219 0.219 Sample 15 20 12.4 31.70.208 0.200 Sample 16 20 12.4 31.7 0.208 0.200 Sample 17 20 12.4 31.70.208 0.200 Sample 18 20 12.4 31.7 0.208 0.200 Sample 19 20 12.4 31.70.208 0.200 Sample 20 30 19.3 44.7 0.192 0.173 Sample 21 30 19.3 44.70.192 0.173 Sample 22 30 19.3 44.7 0.192 0.173 Sample 23 30 19.3 44.70.192 0.173 Sample 24 40 26.3 61.2 0.182 0.185 Sample 25 40 26.3 61.20.182 0.185 Sample 26 40 26.3 61.2 0.182 0.185 Mixing Ratio SphericalSpherical Graphite 2 Graphite Particle Size Distribution 1/ D50 D10 D90log(D50) − log(D90) − Spherical (μm) (μm) (μm) log(D10) log(D50)Graphite 2 Sample 1 5 3.1 8.1 0.208 0.210 70/30 Sample 2 10 6.6 15.70.180 0.196 70/30 Sample 3 12 7.6 18.3 0.198 0.183 70/30 Sample 4 5 3.18.1 0.208 0.210 70/30 Sample 5 8 4.9 12.7 0.213 0.201 70/30 Sample 6 117.2 17.4 0.184 0.199 70/30 Sample 7 12 7.6 18.3 0.198 0.183 70/30 Sample8 14 9.3 21.5 0.178 0.186 70/30 Sample 9 16 10.8 24.1 0.171 0.178 70/30Sample 10 12 7.6 18.3 0.198 0.183 70/30 Sample 11 12 7.6 18.3 0.1980.183 70/30 Sample 12 14 9.3 21.5 0.178 0.186 70/30 Sample 13 16 10.824.1 0.171 0.178 70/30 Sample 14 12 7.3 19.8 0.216 0.217 70/30 Sample 1510 6.6 15.7 0.180 0.196 65/35 Sample 16 10 6.6 15.7 0.180 0.196 70/30Sample 17 10 6.6 15.7 0.180 0.196 80/20 Sample 18 10 6.6 15.7 0.1800.196 85/15 Sample 19 10 6.6 15.7 0.180 0.196 90/10 Sample 20 12 7.618.3 0.198 0.183 65/35 Sample 21 12 7.6 18.3 0.198 0.183 80/20 Sample 2212 7.6 18.3 0.198 0.183 85/15 Sample 23 12 7.6 18.3 0.198 0.183 90/10Sample 24 15 9.8 22.3 0.185 0.172 65/35 Sample 25 15 9.8 22.3 0.1850.172 70/30 Sample 26 15 9.8 22.3 0.185 0.172 80/20

TABLE 2 Spherical Graphite 1 Particle Size Distribution D90 log(D50) −log(D90) − D50 (μm) D10 (μm) (μm) log(D10) log(D50) Sample 27 40 26.361.2 0.182 0.185 Sample 28 40 26.3 61.2 0.182 0.185 Sample 29 20 12.431.7 0.208 0.200 Sample 30 30 19.3 44.7 0.192 0.173 Sample 31 40 26.361.2 0.182 0.185 Sample 32 — — — — — Sample 33 — — — — — Sample 34 — — —— — Sample 35 15  9.3 24.4 0.208 0.211 Sample 36 15  9.3 24.4 0.2080.211 Sample 37 45 29.8 68.4 0.179 0.182 Sample 38 50 31.8 75.0 0.1970.176 Sample 39 30 19.3 44.7 0.192 0.173 Sample 40 20 12.4 31.7 0.2080.200 Sample 41 30 19.3 44.7 0.192 0.173 Sample 42 30 19.3 44.7 0.1920.173 Sample 43 40 26.3 61.2 0.182 0.185 Sample 44 20 12.4 31.7 0.2080.200 Sample 45 30 17.8 44.7 0.227 0.173 Sample 46 30  9.9 44.7 0.4810.173 Sample 47 30 19.3 44.7 0.192 0.173 Sample 48 30 19.3 44.7 0.1920.173 Sample 49 30 17.8 44.7 0.227 0.173 Sample 50 30  9.9 44.7 0.4810.173 Sample 51 30 19.3 50.0 0.192 0.222 Sample 52 30 19.3 74.3 0.1920.394 Mixing Ratio Spherical Spherical Graphite 2 Graphite Particle SizeDistribution 1/ D50 D10 D90 log(D50) − log(D90) − Spherical (μm) (μm)(μm) log(D10) log(D50) Graphite 2 Sample 27 15 9.8 22.3 0.185 0.17285/15 Sample 28 15 9.8 22.3 0.185 0.172 90/10 Sample 29 — — — — — 100/0 Sample 30 — — — — — 100/0  Sample 31 — — — — — 100/0  Sample 32 5 3.18.1 0.208 0.210  0/100 Sample 33 11 7.2 17.4 0.184 0.199  0/100 Sample34 16 10.8 24.1 0.171 0.178  0/100 Sample 35 5 3.1 8.1 0.208 0.210 70/30Sample 36 7 4.3 11.3 0.212 0.208 70/30 Sample 37 12 7.6 18.3 0.198 0.18370/30 Sample 38 12 7.6 18.3 0.198 0.183 70/30 Sample 39 2 1.3 3.3 0.1870.217 70/30 Sample 40 3 1.9 4.8 0.198 0.204 70/30 Sample 41 3 1.9 4.80.198 0.204 70/30 Sample 42 18 12.4 26.5 0.162 0.168 70/30 Sample 43 1812.4 26.5 0.162 0.168 70/30 Sample 44 12 7.6 18.3 0.198 0.183 70/30Sample 45 12 7.6 18.3 0.198 0.183 70/30 Sample 46 12 7.6 18.3 0.1980.183 70/30 Sample 47 12 7.0 18.3 0.234 0.183 70/30 Sample 48 12 4.118.3 0.466 0.183 70/30 Sample 49 12 7.0 18.3 0.234 0.183 70/30 Sample 5012 4.1 18.3 0.466 0.183 70/30 Sample 51 12 7.6 18.3 0.198 0.183 70/30Sample 52 12 7.6 18.3 0.198 0.183 70/30

TABLE 3 Spherical Graphite 1 Particle Size Distribution D50 D10 D90log(D90) − (μm) (μm) (μm) log(D50) − log(D10) log(D50) Sample 53 30 19.344.7 0.192 0.173 Sample 54 30 19.3 44.7 0.192 0.173 Sample 55 30 19.350.0 0.192 0.222 Sample 56 30 19.3 74.3 0.192 0.394 Sample 57 30 17.351.5 0.239 0.235 Sample 58 30 13.5 62.3 0.347 0.317 Sample 59 30 19.344.7 0.192 0.173 Sample 60 30 19.3 44.7 0.192 0.173 Sample 61 30 17.351.5 0.239 0.235 Sample 62 30 13.5 62.3 0.347 0.317 Sample 63 20 12.431.7 0.208 0.200 Sample 64 30 19.3 44.7 0.192 0.173 Sample 65 40 26.361.2 0.182 0.185 Sample 66 20 12.4 31.7 0.208 0.200 Sample 67 30 19.344.7 0.192 0.173 Sample 68 40 26.3 61.2 0.182 0.185 Mixing RatioSpherical Spherical Graphite 2 Graphite Particle Size Distribution 1/D50 D10 D90 log(D50) − log(D90) − Spherical (μm) (μm) (μm) log(D10)log(D50) Graphite 2 Sample 53 12 7.6 20.0 0.198 0.222 70/30 Sample 54 127.6 28.4 0.198 0.374 70/30 Sample 55 12 7.6 20.0 0.198 0.222 70/30Sample 56 12 7.6 28.4 0.198 0.374 70/30 Sample 57 12 7.6 18.3 0.1980.183 70/30 Sample 58 12 7.6 18.3 0.198 0.183 70/30 Sample 59 12 7.021.1 0.234 0.245 70/30 Sample 60 12 5.4 28.3 0.347 0.373 70/30 Sample 6112 7.0 21.1 0.234 0.245 70/30 Sample 62 12 5.4 28.3 0.347 0.373 70/30Sample 63 10 6.6 15.7 0.180 0.196 60/40 Sample 64 12 7.6 18.3 0.1980.183 60/40 Sample.65 15 9.8 22.3 0.185 0.172 60/40 Sample 66 10 6.615.7 0.180 0.196 95/5  Sample 67 12 7.6 18.3 0.198 0.183 95/5  Sample 6815 9.8 22.3 0.185 0.172 95/5 

In Table 1 to Table 3, 10% cumulative particle size from the side of asmall particle size, when the particle size distribution is measured bya laser diffraction method, is designated by D10. Then, 50% cumulativeparticle size from the side of a small particle size is designated byD50, and 90% cumulative particle size from the side of a small particlesize is designated by D90. Further, the spherical graphite of the largeparticle size of the spherical graphite having different averageparticle sizes is called spherical graphite 1. The spherical graphite ofthe small particle size is called spherical graphite 2.

Now, a method for producing the lithium-ion secondary batteries will bespecifically described below as Sample 1 to Sample 68.

To manufacture the lithium-ion secondary battery, a cathode was firstmanufactured. When the cathode was formed, lithium cobaltate (LiCoO₂) of92 wt % as a cathode active material was added to polyvinylidenefluoride (referred to hereinafter as PVdF) of 3 wt % as a binding agent,graphite of 5 wt % as a conductive material, and N-methyl-2-pyrrolidone(referred to hereinafter as NMP) as a solvent. The mixture was kneadedand dispersed by a planetary mixer to prepare cathode composite mixture.Then, the cathode composite mixture was uniformly applied to a singlesurface of an elongated aluminum foil having the thickness of 20 μm as acathode current collector by using a die coater as an applicator, anddried at 100° C. for 24 hours under a pressure reduced state. Then, thealuminum foil thus obtained was compression-molded by a roll pressmachine and cut to a width of 48 mm and a length of 300 mm. In such away, the plural cathodes were produced.

Then, the anode was manufactured. When the anode was formed, mixtures oftwo kinds of spherical graphite, shown in the columns of Samples 1 to 68in Table 1 to Table 3, which were mixed in the mixing ratios shown inthe columns of Samples 1 to 68 in Table 1 to Table 3, were respectivelyemployed as anode active materials. The anode active materials ofSamples 1 to 68 of 90 wt % were respectively added to PVdF of 10 wt % asa binding agent and NMP as a solvent, and the mixtures were kneaded anddispersed by a planetary mixer to respectively manufacture anodecomposite mixtures using Samples 1 to 68. Then, the anode compositemixtures were uniformly applied to single surfaces of elongated copperfoils having the thickness of 20 μm as anode current collectors by usinga die coater as an applicator, and dried at 120° C. for 24 hours under apressure reduced state. Then, the copper foils thus obtained werecompression-molded by a roll press machine and cut to width of 50 mm andlength of 310 mm. In such a way, anodes of Samples 1 to 68 wereproduced.

Subsequently, electrolyte layers were respectively formed on the mainsurfaces of the plural cathodes and the anodes formed as describedabove. When the electrolyte layer was formed, non-aqueous electrolytesolution was prepared in which LiPF₆ was dissolved in a solvent obtainedby mixing ethylene carbonate of 60 wt % with propylene carbonate of 40wt % in the ratio of 0.8 mol/kg relative to the weight of the solvent.Then, the non-aqueous electrolyte solution was mixed and agitated withPVdF with which hexafluoropropylene was copolymerized in the ratio of 6%and dimethyl carbonate to prepare gel electrolyte solution in a solstate. Then, the gel electrolyte solution was applied respectively tothe main surfaces of the cathodes and the anodes to evaporate dimethylcarbonate. In such a way, the electrolyte layers composed of the gelelectrolytes were respectively formed on the main surfaces of the pluralcathodes and the anodes.

Then, while porous polyethylene films having the thickness of 10 μm wereinterposed as separators between the cathodes and the anodes having theelectrolyte layers formed on their main surfaces as described above, thecathodes and the anodes were stuck together so that the electrolytelayers were opposed to each other. Then, the obtained members werespirally coiled in the longitudinal directions of the cathodes in flatforms to form the battery elements of Samples 1 to 68. At this time,elongated cathode terminals made of aluminum were attached to arbitrarypositions of the cathodes and elongated anode terminals made of nickelwere attached to arbitrary positions of the anodes.

Then, while the cathode terminals and the anode terminals provided inthe battery elements of these Samples 1 to 68 were drawn outside, thebattery elements were accommodated in outer package materials of threelayer structures that aluminum foils having the thickness of 50 μm weresandwiched in between polyolefine films having the thickness of 30 μm.At this time, the battery elements were accommodated in the outerpackage materials by providing propylene resin pieces showing adhesivecharacteristics between the cathode terminals and the anode terminals,and the outer package materials. Accordingly, in the battery elements,short-circuits of the cathode terminals and the anode terminals wereprevented through the aluminum foils of the outer package materials, orthe deterioration of the air-tightness or the like was prevented. Then,the peripheral edges of the outer package materials in which the batteryelements were accommodated were stuck together to seal the batteryelements in the outer package materials. As described above, thelithium-ion secondary batteries of Samples 1 to 68 were produced. In thefollowing description, the lithium-ion secondary battery is referred tosimply as a battery for convenience.

Then, for each of the batteries of Samples 1 to 68 manufactured asdescribed above, the volume density of an anode composite mixture layer,an initial charging and discharging efficiency, an initial dischargingcapacity, discharge load characteristics, and a discharging capacitymaintaining/retention ratio after a 500 cycle were measured.

The evaluated results of the volume density of the anode compositemixture layer, the initial charging and discharging efficiency, theinitial discharging capacity, the discharge load characteristic, and thedischarging capacity maintaining/retention ratio after the 500 cycle ineach Sample are shown in Table 4 to Table 6.

TABLE 4 Volumetric Density of Anode Initial Charging Composite MixtureAnd Discharging Initial Discharging Layer (g/cm³) Efficiency (%)Capacity (mAh) Sample 1 1.70 83 836 Sample 2 1.70 85 849 Sample 3 1.7089 885 Sample 4 1.70 83 833 Sample 5 1.70 88 890 Sample 6 1.70 91 909Sample 7 1.70 92 917 Sample 8 1.70 93 927 Sample 9 1.70 88 885 Sample 101.70 91 912 Sample 11 1.70 90 898 Sample 12 1.70 90 910 Sample 13 1.7088 890 Sample 14 1.70 89 900 Sample 15 1.70 86 855 Sample 16 1.70 94 847Sample 17 1.70 86 862 Sample 18 1.70 86 859 Sample 19 1.70 83 833 Sample20 1.70 90 904 Sample 21 1.70 89 893 Sample 22 1.70 90 898 Sample 231.70 89 894 Sample 24 1.70 88 883 Sample 25 1.70 88 879 Sample 26 1.7091 915 Capacity Maintaining/retention Discharging Load Ratio after 500Cycle Characteristics (%) (%) Sample 1 85 75 Sample 2 85 81 Sample 3 8784 Sample 4 85 75 Sample 5 87 77 Sample 6 91 82 Sample 7 92 83 Sample 891 79 Sample 9 92 75 Sample 10 90 80 Sample 11 88 81 Sample 12 88 75Sample 13 86 75 Sample 14 86 75 Sample 15 86 81 Sample 16 85 80 Sample17 87 82 Sample 18 85 79 Sample 19 87 81 Sample 20 86 81 Sample 21 91 82Sample 22 89 83 Sample 23 92 84 Sample 24 89 80 Sample 25 90 79 Sample26 92 82

TABLE 5 Volumetric Density of Anode Initial Charging/ Composite MixtureDischarging Initial Discharging Layer (g/cm³) Efficiency (%) Capacity(mAh) Sample 27 1.70 91 911 Sample 28 1.70 86 863 Sample 29 1.68 82 821Sample 30 1.67 84 835 Sample 31 1.67 84 840 Sample 32 1.64 77 777 Sample33 1.66 76 759 Sample 34 1.66 76 775 Sample 35 1.68 76 764 Sample 361.68 78 784 Sample 37 1.68 77 769 Sample 38 1.66 81 811 Sample 39 1.7072 727 Sample 40 1.70 80 810 Sample 41 1.70 79 795 Sample 42 1.68 77 783Sample 43 1.68 78 785 Sample 44 1.70 77 781 Sample 45 1.70 77 780 Sample46 1.69 79 799 Sample 47 1.68 77 770 Sample 48 1.66 74 744 Sample 491.65 73 735 Sample 50 1.63 69 682 Sample 51 1.68 79 799 Sample 52 1.6780 804 Capacity Maintaining/retention Discharging Load Ratio after 500Cycle Characteristics (%) (%) Sample 27 91 81 Sample 28 91 77 Sample 2983 57 Sample 30 84 58 Sample 31 84 49 Sample 32 78 37 Sample 33 80 41Sample 34 81 44 Sample 35 74 69 Sample 36 77 73 Sample 37 87 72 Sample38 87 65 Sample 39 70 64 Sample 40 76 72 Sample 41 72 68 Sample 42 79 73Sample 43 81 68 Sample 44 78 68 Sample 45 79 75 Sample 46 79 71 Sample47 79 68 Sample 48 80 69 Sample 49 73 66 Sample 50 70 63 Sample 51 81 72Sample 52 88 74

TABLE 6 Volumetric Density of Anode Initial Charging/ Composite MixtureDischarging Initial Discharging Layer (g/cm³) Efficiency (%) Capacity(mAh) Sample 53 1.68 77 792 Sample 54 1.69 80 798 Sample 55 1.67 79 791Sample 56 1.65 75 755 Sample 57 1.70 79 790 Sample 58 1.69 81 814 Sample59 1.70 79 801 Sample 60 1.68 80 806 Sample 61 1.68 79 795 Sample 621.65 75 755 Sample 63 1.68 79 829 Sample 64 1.68 81 815 Sample 65 1.6780 802 Sample 66 1.68 80 798 Sample 67 1.67 80 808 Sample 68 1.68 80 804Capacity Maintaining/retention Discharging Load Ratio after 500 CycleCharacteristics (%) (%) Sample 53 81 71 Sample 54 90 73 Sample 55 81 67Sample 56 90 68 Sample 57 79 67 Sample 58 80 72 Sample 59 79 66 Sample60 74 69 Sample 61 74 59 Sample 62 72 62 Sample 63 80 79 Sample 64 81 80Sample 65 83 78 Sample 66 81 75 Sample 67 84 78 Sample 68 84 72

In each Sample, a constant-current and constant-voltage chargingoperation of 0.2 C and 4.2 V was carried out and a constant-currentdischarging operation having a current value of 0.2 C up to 3 V wascarried out. An initial discharging capacity is a discharging capacitywhen charging and discharging operations were performed under theabove-described conditions. In this Example, Samples having the initialdischarging capacity of 830 mAh or higher were considered to be goodproducts. An initial charging and discharging efficiency is a ratio ofthe initial discharging capacity relative to an obtained initialcharging capacity. In this Example, Samples having the initial chargingand discharging efficiency of 83% or higher were considered to be goodproducts. Discharge load characteristics show a ratio of the dischargingcapacity upon discharging under 3 C relative to the discharging capacityupon discharging under 0.2 C. In this Example, Samples having thedischarge load characteristics of 85% or higher were considered to begood products. A discharging capacity maintaining/retention ratio aftera 500 cycle is a ratio of a discharging capacity of a 500th cyclerelative to the initial discharging capacity when the charging anddischarging operations are carried out 500 times under theabove-described conditions. In this Example, Samples having thedischarging capacity maintaining/retention ratio after a 500 cycle of75% or higher were considered to be good products.

As apparent from the evaluated results shown in Table 4 and Table 5, inSample 7 using the mixture of spherical graphite of a large particlesize and spherical graphite of a small particle size as an anode activematerial, the volume density of the anode composite mixture layer ishigher than those of Samples 29 to 31 using only spherical graphite of alarge particle size for an anode active material. Further, the initialcharging and discharging efficiency, the initial discharging capacity,and the discharge load characteristics of Sample 7 are higher than thoseof Samples 29 to 31. Especially, the discharging capacitymaintaining/retention ratio after a 500 cycle of Sample 7 is extremelyhigher than those of Samples 29 to 31.

In Samples 29 to 31, since the spherical graphite of a small particlesize, whose average particle size is located within a range of 5 μm to16 μm, is not mixed in the anode active material, clearances in theanode composite mixture layer, produced due to the contact of two ormore spherical graphite of a large particle size, are not filled withthe spherical graphite. Thus, the volume density of the anode compositemixture layer is decreased. Then, when the clearances are present in theanode composite mixture layer, while charging and discharging operationsare repeated, the clearances become large so that the contact of thespherical graphite is separated to increase an ionic resistance to theelectrolyte of an anode side. Thus, the capacity of a battery isdecreased and the discharge load characteristics or cycliccharacteristics are deteriorated.

As apparent from the evaluated results shown in Table 4 and Table 5, inSample 7 using the mixture of the spherical graphite of the largeparticle size and the spherical graphite of the small particle size asan anode active material, the volume density of the anode compositemixture layer is higher than those of Sample 32 to 34 using only thespherical graphite of the small particle size for an anode activematerial. Further, the initial charging and discharging efficiency, theinitial discharging capacity, and the discharge load characteristics ofSample 7 are higher than those of Samples 32 to 34. Especially, thedischarging capacity maintaining/retention ratio after a 500 cycle ofSample 7 is extremely higher than those of Samples 32 to 34.

In Samples 32 to 34, since the spherical graphite of the large particlesize whose average particle size is located within a range of 20 μm to40 μm is not mixed in the anode active material, the anode compositemixture layer is filled with the spherical graphite without spaces.Thus, pressure is excessively exerted on the spherical graphite under acompression molding upon manufacturing the anode so that the surfaces ofparticles of the spherical graphite are broken. Accordingly, in Samples32 to 34, since the anode active material cracks under the compressionmolding upon manufacturing the anode, the volume density of the anodecomposite mixture layer is hardly increased. In Samples 32 to 34, whenthe surfaces of the particles of the spherical graphite are broken, abulk part high in reactivity with the electrolyte is exposed. Thus, theanode is degraded due to the reaction with the electrolyte to decreasethe discharging capacity and lower the initial charging and dischargingefficiency or the initial discharging capacity. Further, since there isno space for retaining the electrolyte in the anode composite mixturelayer, the ionic resistance to the electrolyte of the anode side isincreased and battery characteristics such as the discharge loadcharacteristics or the cyclic characteristics are deteriorated.

On the contrary, in Sample 7, the mixture of the spherical graphite ofthe large particle size and the spherical graphite of the small particlesize is used for the anode active material. Since the spherical graphiteof the large particle size decreases its surface area relative to thespherical graphite of the small particle size, the reaction with theelectrolyte is reduced to suppress the decrease of the capacity of thebattery. Further, in Sample 7, since the spherical graphite of the largeparticle size has a large volume relative to surface area, a bulk partis large relative to the spherical graphite of the small particle sizeto increase the capacity of the battery. Further, in Sample 7, thespherical graphite of the large particle size forms clearances ofsuitable sizes in the anode composite mixture layer to retain theelectrolyte. In Sample 7, the clearances in the anode composite mixturelayer are efficiently filled with the spherical graphite of the smallparticle size, while spaces capable of retaining a suitable amount ofelectrolyte are left unfilled.

Accordingly, in Sample 7, the mixture of the spherical graphite of thelarge particle size and the spherical graphite of the small particlesize is used for the anode active material, so that the volume densityof the anode composite mixture layer is increased and the capacity ofthe battery is increased. Therefore, the volume density of the anodecomposite mixture layer is increased, the initial charging anddischarging efficiency and the initial discharging capacity can beincreased and the ionic resistance to the electrolyte of the anode sideis decreased. Thus, the deterioration of the discharge loadcharacteristics and the cyclic characteristics can be prevented.

As described above, the use of the mixture of spherical graphite oflarge particle size and spherical graphite of the small particle sizefor the anode active material is remarkably effective in manufacturing abattery having a high volume density of the anode composite mixturelayer and excellent in battery characteristics such as charging anddischarging cyclic characteristics.

As apparent from the evaluated results shown in Table 4 and Table 5, inSample 1 to 13 in which the average particle size of the sphericalgraphite of the large particle size is located within a range of 20 μmto 40 μm, the volume density of the anode composite mixture layer ishigher than those of Samples 35 and 36 in which the average particlesize of the spherical graphite of the large particle size is 15 μm. Theinitial charging and discharging efficiency, the initial dischargingcapacity, and the discharging capacity maintaining/retention ratio aftera 500 cycle of Samples 1 to 13 are higher than those of Samples 35 and36.

In Samples 35 and 36, the average particle size of the sphericalgraphite of the large particle size is 15 μm and the particle size istoo small and is not substantially different from the range of theaverage particle size of spherical graphite of small particle size.Accordingly, the surfaces of the particles of the spherical graphite arebroken similarly to Samples 32 to 34. Consequently, in Samples 35 and36, the spherical graphite cracks under the compression molding uponmanufacturing the anode and the volume density of the anode compositemixture layer is hardly increased. Further, due to the same reasons asthose of Samples 32 to 34, the initial charging and dischargingefficiency or the initial discharging capacity is low and the batterycharacteristics such as cyclic characteristics are deteriorated.Further, since the radii of particles are too near to each other,adequate clearances cannot be formed to deteriorate loadcharacteristics.

As apparent from the evaluated results shown in Table 4 and Table 5, inSample 1 to 13, in which the average particle size of the sphericalgraphite of the large particle size is located within a range of 20 μmto 40 μm, the volume density of the anode composite mixture layer ishigher than those of Samples 37 and 38 in which the average particlesize of the spherical graphite of the large particle size is 45 μm orlarger. The initial charging and discharging efficiency, the initialdischarging capacity, and the discharging capacity maintaining/retentionratio after a 500 cycle of Samples 1 to 13 are higher than those ofSamples 37 and 38.

In Samples 37 and 38, the average particle size of the sphericalgraphite of the large particle size is 45 μm or larger and the particlesize is too large. Accordingly, the volume density of the anodecomposite mixture layer is hardly increased under the compressionmolding upon manufacturing the anode. Since particles crack due to thecompression molding, the charging and discharging efficiency and thedischarging capacity are decreased, and cyclic characteristics aredeteriorated.

On the other hand, in Samples 1 to 13, the average particle size of thespherical graphite of the large particle size of two kinds of sphericalgraphite used as the anode active material is an appropriate sizelocated within a range of 20 μm to 40 μm. Thus, the spherical graphiteof the large particle decreases its surface area relative to that of thespherical graphite of the small particle size, so that a reaction withthe electrolyte is reduced to suppress the deterioration of the capacityof the battery. Further, in Samples 1 to 13, since the sphericalgraphite of the large particle size having an appropriate size increasesa volume relative to the surface area, the bulk part becomes largerelative to the spherical graphite of the small particle size toincrease the capacity of the battery. Further, in Samples 1 to 13, theaverage particle size of the spherical graphite of the large particlesize is located within an adequate range. Accordingly, the clearances ofsuitable sizes can be formed in the anode composite mixture layer andare efficiently filled with the spherical graphite of the small particlesize, while spaces are left unfilled in which a suitable amount ofelectrolyte can be retained.

Therefore, in Samples 1 to 13, the volume density of the anode compositemixture layer is high and the initial charging and dischargingefficiency or the initial discharging capacity can be increased.Further, the ionic resistance relative to the electrolyte of the anodeside is decreased to prevent the deterioration of the discharge loadcharacteristics or the cyclic characteristics.

As described above, when the battery is manufactured by employing themixture of the spherical graphite of the large particle size and thespherical graphite of the small particle size for the anode activematerial, the average particle size of the spherical graphite of thelarge particle size is located within a range of 20 μm to 40 μm. The useof the above-described range is very effective in manufacturing abattery having a high volume density of the anode composite mixturelayer and excellent in its battery characteristics such as charging anddischarging efficiency characteristics, discharging capacitycharacteristics, discharge load characteristics and charging, anddischarging cyclic characteristics.

As apparent from the evaluated results shown in Table 4 and Table 5, inSample 1 to 13, in which the average particle size of the sphericalgraphite of the small particle size is located within a range of 5 μm to16 μm, the initial charging and discharging efficiency, the initialdischarging capacity, the discharge load characteristics, and thedischarging capacity maintaining/retention ratio after a 500 cycle arehigher than those of Samples 39 to 41 in which the average particle sizeof the spherical graphite of the small particle size is 3 μm or smaller.

In Samples 39 to 41, since the average particle size of the sphericalgraphite of the small particle size is 3 μm or smaller and the particlesize is too small, not only the clearances of the anode compositemixture layer, but also spaces for retaining the electrolyte are filledwith the spherical graphite of the small particle size. Thus, anelectric contact between the anode and the electrolyte is decreased toincrease an electric resistance of the anode side. As a result, thecapacity of the battery is reduced, cyclic characteristics aredeteriorated, and especially, load characteristics are degraded.

As apparent from the evaluated results shown in Table 3 and Table 5, inSamples 1 to 13, in which the average particle size of the sphericalgraphite of the small particle size is located within a range of 5 μm to16 μm, the volume density of the anode composite mixture layer, theinitial charging and discharging efficiency, the initial dischargingcapacity, the discharge load characteristics, and the dischargingcapacity maintaining/retention ratio after a 500 cycle are higher thanthose of Samples 42 and 43 in which the average particle size of thespherical graphite of the small particle size is 18 μm.

In Samples 42 and 43, since the average particle size of the sphericalgraphite of a small particle size is 18 μm and the particle size is toolarge and is not substantially different from a range of the averageparticle size of the spherical graphite of the large particle size,clearances in the anode composite mixture layer produced due to thecontact of two or more spherical graphite of a large particle size arenot properly filled with the spherical graphite of the small particlesize similarly to Samples 29 to 31. Thus, the volume density of theanode composite mixture layer is decreased. Then, in Samples 42 and 43,when the clearances are present in the anode composite mixture layer,while charging and discharging operations are repeated, the clearancesbecome large so that the contact of the spherical graphite is separatedto increase an ionic resistance to the electrolyte of an anode side.Thus, the capacity of a battery is decreased and the discharge loadcharacteristics or the cyclic characteristics are deteriorated. Further,in Samples 42 and 43, since there is no difference in average particlesize between the spherical graphite of the small particle size and thespherical graphite of the large particle size, pressure is excessivelyexerted on the spherical graphite under the compression molding uponforming the anode. Thus, the spherical graphite cracks to expose thebulk part of the spherical graphite high in its reactivity with anon-aqueous electrolyte. The anode is deteriorated due to the reactionwith the electrolyte to decrease the discharging capacity.

On the other hand, in Samples 1 to 13, the average particle size of thespherical graphite of the small particle size of two kinds of sphericalgraphite used as the anode active material is an appropriate sizelocated within a range of 5 μm to 16 μm. Accordingly, the clearances inthe anode composite mixture layer are efficiently filled with thespherical graphite of the small particle size while spaces are leftunfilled in which a suitable amount of electrolyte can be retained.

Therefore, in Samples 1 to 13, the volume density of the anode compositemixture layer becomes high and the capacity of the battery is increased,and the initial charging and discharging efficiency and the initialdischarging capacity can be increased. Further, theionic resistancerelative to the electrolyte of the anode side is decreased to preventthe deterioration of the discharge load characteristics or the cycliccharacteristics.

As described above, when the battery is manufactured by employing themixture of the spherical graphite of the large particle size and thespherical graphite of the small particle size for the anode activematerial, the average particle size of the spherical graphite of thesmall particle size is located within a range of 5 μm to 16 μm. The useof the above-described range is very effective in manufacturing abattery having a high volume density of the anode composite mixturelayer and excellent in its battery characteristics such as charging anddischarging efficiency characteristics, discharging capacitycharacteristics, discharge load characteristics, and charging anddischarging cyclic characteristics.

As apparent from the evaluated results shown in Table 4 and Table 5, inSample 2, in which the average particle size of the spherical graphiteof the small particle size is 0.55 times the average particle size ofthe spherical graphite of the large particle size or smaller, theinitial charging and discharging efficiency, the initial dischargingcapacity, the discharge load characteristics, and the dischargingcapacity maintaining/retention ratio after a 500 cycle are higher thanthose of Sample 44 in which the average particle size of the sphericalgraphite of the small particle size is 0.6 times the average particlesize of the spherical graphite of the large particle size.

In Sample 44, since the average particle size of the spherical graphiteof the small particle size is 0.6 times the average particle size of thespherical graphite of the large particle size and there is no differencein average particle size between the spherical graphite of the smallparticle size and the spherical graphite of the large particle size,pressure is excessively exerted on the spherical graphite under thecompression molding upon forming the anode. Thus, the spherical graphitecracks to expose the bulk part of the spherical graphite high in itsreactivity with an electrolyte. The anode is deteriorated due to thereaction with the electrolyte to decrease the discharging capacity.Further, in Sample 44, the anode is deteriorated to increase the ionicresistance to the electrolyte of the anode side. Thus, the dischargeload characteristics or the cyclic characteristics are deteriorated.

On the other hand, in Sample 2, the average particle size of thespherical graphite of the small particle size is 0.55 times the averageparticle size of the spherical graphite of the large particle size orsmaller, and the particle size of the spherical graphite of the smallparticle size is set to be suitably small relative to the particle sizeof the spherical graphite of the large particle size. Accordingly, anoperational effect by the spherical graphite of the large particle sizeand an operational effect by the spherical graphite of the smallparticle size can be obtained in the same manner as that of theabove-described Sample 7. Therefore, in Sample 2, the anode compositemixture layer is filled with the spherical graphite that does not crack.Thus, the initial charging and discharging efficiency and the initialdischarging capacity can be increased, and the ionic resistance relativeto the electrolyte of the anode side can be lowered to prevent thedeterioration of the discharge load characteristics and the cycliccharacteristics.

As described above, when the battery is manufactured by employing themixture of the spherical graphite of the large particle size and thespherical graphite of the small particle size for the anode activematerial, the average particle size of the spherical graphite of thesmall particle size is 0.55 times the average particle size of thespherical graphite of the large particle size, or smaller. The use ofthe above-described range is very effective in manufacturing a batteryexcellent in its battery characteristics such as charging anddischarging efficiency characteristics, discharging capacitycharacteristics, discharge load characteristics, and charging anddischarging cyclic characteristics.

In Sample 14, shown in Table 1, particle size distributions representedby the expressions of log(D50)−log(D10) and log(D90)−log(D50) in thespherical graphite of the large particle size and the spherical graphiteof the small particle size show values not higher than 0.22. Theparticle size distribution areas of two kinds of spherical graphite arecontrolled to be located in narrow ranges. On the other hand, in Samples45 to 50, shown in Table 2, particle size distributions represented bythe expression of log(D50)−log(D10) have values larger than 0.22. Atleast the particle size distribution area of any one of two kinds ofspherical graphite is wide.

Then, as apparent from the evaluated results of Table 4 and Table 5, inSample 14, the initial charging and discharging efficiency, the initialdischarging capacity, and the discharge load characteristics are higherthan those of Samples 45 to 50.

Further, in Samples 51 to 56 shown in Table 2 and Table 3, particle sizedistributions represented by the expression of log(D90)−log(D50) havevalues larger than 0.22. At least the particle size distribution area ofany one of two kinds of spherical graphite is wide.

Then, as apparent from the evaluated results shown in Table 4 to Table6, in Sample 14, the volume density of the anode composite mixture layeris higher than those of Samples 51 to 56. The initial charging anddischarging efficiency, the initial discharging capacity, and thedischarging capacity maintaining/retention ratio after a 500 cycle ofSample 14 are higher than those of Samples 51 to 56.

Further, in Samples 57 to 62, shown in Table 3, particle sizedistributions represented by the expressions of log(D50)−log(D10) andlog(D90)−log(D50) have values larger than 0.22. At least the particlesize distribution area of any one of two kinds of spherical graphite iswide.

Then, as apparent from the evaluated results shown in Table 4 and Table6, in Sample 14, the initial charging and discharging efficiency, theinitial discharging capacity, the discharge load characteristics, andthe discharging capacity maintaining/retention ratio after a 500 cycleof Sample 14 are higher than those of Samples 57 to 62.

As described above, it is understood that Sample in which the particlesize distribution of the anode active material is controlled to benarrow, like Sample 14, has excellent battery characteristics.

As described above, in Samples 45 to 62, the particle size distributionsrepresented by the expressions of log(D50)−log(D10) andlog(D90)−log(D50) in the spherical graphite of the large particle sizeand the spherical graphite of the small particle size have at least onevalue larger than 0.22 and the particle size distribution areas arewidened. Accordingly, it is difficult to efficiently fill the clearancesin the anode composite mixture layer produced due to the contact of twoor more of spherical graphite of the large particle size with thespherical graphite of the small particle size. Further, it is difficultto improve the volume density of the anode composite mixture layer.

Especially, in the spherical graphite of the large particle size, whenthe particle size distribution area of the spherical graphite of largeparticle size represented by the expression of log(D90)−log(D50), notonly the volume density of the anode composite mixture layer isdecreased, but also the clearances exist in the anode composite mixturelayer. Consequently, while charging and discharging operations arerepeated, the clearances become large to separate the contact of thespherical graphite. Thus, an ionic resistance to the electrolyte of theanode side is increased to decrease the capacity of the battery anddeteriorate the discharge load characteristics or the cycliccharacteristics. Further, in this case, pressure is expressively exertedon the spherical graphite under the compression molding uponmanufacturing the anode, so that the spherical graphite cracks to exposethe bulk part of the spherical graphite high in its reactivity with theelectrolyte. A reaction with the electrolyte causes the anode to bedeteriorated and the discharging capacity to be decreased.

On the other hand, in the spherical graphite of the small particle size,when the particle size distribution area of the spherical graphite ofsmall particle size represented by the expression of log(D50)−log(D10)is wide, the anode composite mixture layer is filled with the sphericalgraphite in a fine powdered state without spaces. Thus, there is nospace for retaining the electrolyte in the anode composite mixturelayer. Consequently, an ionic resistance to the electrolyte of the anodeside is increased to deteriorate the discharge load characteristics andthe cyclic characteristics. Further, in this case, the sphericalgraphite in a fine powdered state has a large surface area relative to avolume as compared with the spherical graphite of the large particlesize. This means that, while a capacity is small, reactivity with theelectrolyte is high to decrease the capacity. Accordingly, in thespherical graphite of the small particle size, the particle sizedistribution area of the spherical graphite of smaller particle size iswide. In this case, the discharging capacity is decreased due to thereaction with the electrolyte to decrease the initial charging anddischarging efficiency and the initial discharging capacity.

As compared therewith, in Sample 14, the particle size distributionsrepresented by the expressions of log(D50)−log(D10) andlog(D90)−log(D50) in the spherical graphite of the large particle sizeand the spherical graphite of the small particle size have values notlarger than 0.22 and the particle size distribution areas of two kindsof spherical graphite are controlled to be narrow. Therefore, theoperational effect by the spherical graphite of the large particle sizeand the operational effect by the spherical graphite of the smallparticle size can be obtained like the above-described Sample 7.Accordingly, in Sample 14, the volume density of the anode compositemixture layer is increased to increase the capacity of the battery.Thus, the volume density of the anode composite mixture layer is high,the initial charging and discharging efficiency and the initialdischarging capacity can be increased and the ionic resistance to theelectrolyte of the anode side can be lowered to prevent thedeterioration of the discharge load characteristics and the cycliccharacteristics.

As described above, the battery is manufactured by employing the mixtureof the spherical graphite of the large particle size and the sphericalgraphite of the small particle size for the anode active material. Inthis case, it is very effective to control the particle sizedistribution areas in the spherical graphite of the large particle sizeand the spherical graphite of the small particle size to be narrow inmanufacturing the battery having the high volume density of the anodecomposite mixture layer and excellent in its battery characteristicssuch as charging and discharging efficiency characteristics, dischargingcapacity characteristics, discharge load characteristics, and chargingand discharging cyclic characteristics.

As apparent from the evaluated results shown in Table 4 to Table 6, inSamples 15 to 28, in which the spherical graphite of the large particlesize is mixed with the spherical graphite of the small particle sizewithin a range of the weight ratio of 65:35 through 90:10, the volumedensity of the anode composite mixture layer, the initial charging anddischarging efficiency, the initial discharging capacity, and thedischarge load characteristics are higher than those of Samples 63 to 65in which the spherical graphite of the large particle size is mixed withthe spherical graphite of the small particle size in the weight ratio of60:40.

In Samples 63 to 65, the spherical graphite of the large particle sizeis mixed in the weight ratio as small as 60% relative to all of thespherical graphite. The spherical graphite of the small particle sizehaving a large surface area and a high reactivity with the electrolyteis too much. Accordingly, the capacity and safety of the batterylowered. Further, in Samples 63 to 65, since a quantity of the sphericalgraphite of the small particle size is also more than a proper value,the volume density cannot be increased. Further, even spaces forretaining the electrolyte in the anode active material are filled withthe spherical graphite of the small particle size. Thus, the electrolyterelative to the anode composite mixture layer is decreased and the ionicresistance to the electrolyte of the anode side is increased todeteriorate the discharge load characteristics.

As apparent from the evaluated results shown in Table 4 to Table 6, inSamples 15 to 28, in which the spherical graphite of the large particlesize is mixed with the spherical graphite of the small particle sizewithin a range of the weight ratio of 65:35 through 90:10, the volumedensity of the anode composite mixture layer, the initial charging anddischarging efficiency, the initial discharging capacity, the dischargeload characteristics, and the discharging capacity maintaining/retentionratio after a 500 cycle are higher than those of Samples 66 to 68 inwhich the spherical graphite of the large particle size is mixed withthe spherical graphite of the small particle size in the weight ratio of95:5.

In Samples 66 to 68, the spherical graphite of the large particle sizeis mixed in the weight ratio as high as 95% relative to all of thespherical graphite. A quantity of the spherical graphite of the smallparticle size is too small. Therefore, the clearances in the anodecomposite mixture layer are hardly appropriately filled with thespherical graphite of the small particle size. Thus, the volume densityof the anode composite mixture layer is decreased to lower the capacityof the battery. Further, in Samples 66 to 68, not only the volumedensity of the anode composite mixture layer is decreased, but also theclearances exist in the anode composite mixture layer. Thus, whilecharging and discharging operations are repeated, the clearances becomelarge so that the contact of the spherical graphite is separated toincrease the ionic resistance to the electrolyte of the anode side,lower the capacity of the battery, and deteriorate the discharge loadcharacteristics and the cyclic characteristics.

On the contrary, in Samples 15 to 28, the spherical graphite of thelarge particle size is mixed with the spherical graphite of the smallparticle size within a range of weight ratio of 65:35 through 90:10. Themixing ratio of two kinds of spherical graphite is located within aproper range. Accordingly, the operational effect by the sphericalgraphite of the large particle size and the operational effect by thespherical graphite of the small particle size can be obtained like theabove-described Sample 7. Therefore, in Samples 15 to 28, the volumedensity of the anode composite mixture layer is increased to increasethe capacity of the battery. Thus, the volume density of the anodecomposite mixture layer is high, the initial charging and dischargingefficiency and the initial discharging capacity can be increased, andthe ionic resistance to the electrolyte of the anode side can be loweredto prevent the deterioration of the discharge load characteristics andthe cyclic characteristics.

As described above, when a battery is manufactured by employing themixture of the spherical graphite of the large particle size and thespherical graphite of the small particle size for the anode activematerial, it is very effective to mix the spherical graphite of largeparticle size with the spherical graphite of the small particle sizewithin a range of weight ratio of 65:35 through 90:10 in manufacturingthe battery having a high volume density of the anode composite mixturelayer and excellent in its battery characteristics such as charging anddischarging efficiency characteristics, discharging capacitycharacteristics, discharge load characteristics, and charging anddischarging cyclic characteristics.

Now, as non-electrolyte batteries to which the present invention isapplied, Samples 69 to 74 were manufactured wherein the anode activematerial in the above-described Sample 1 was changed to flake naturalgraphite, crushed artificial graphite obtained from bulk mesophase orthe like, and a spherical carbonaceous material obtained by applying aspherical treatment and a surface treatment to hard carbon. TheseSamples, Samples 69 to 74, were produced by using anode activesmaterials having conditions such as particle sizes and mixing ratios asshown in Table 7.

TABLE 7 Anode Active Material 1 Particle Size Distribution D50 D10 D90log(D90) − (μm) (μm) (μm) log(D50) − log(D10) log(D50) Sample 69 30 19.046.0 0.198 0.186 Sample 70 30 19.4 44.6 0.189 0.172 Sample 71 30 19.144.8 0.196 0.174 Sample 72 30 17.2 46.6 0.242 0.191 Sample 73 31 20.153.5 0.188 0.237 Sample 74 30 19.3 45.5 0.192 0.181 Mixing Ratio AnodeActive Material Anode Active Material 2 1/ Particle Size DistributionAnode D50 D10 D90 log(D50) − log(D90) − Active (μm) (μm) (μm) log(D10)log(D50) Material 2 Sample 69 12 7.4 18.6 0.210 0.190 70/30 Sample 70 127.6 18.2 0.198 0.181 70/30 Sample 71 12 7.5 18.3 0.204 0.183 70/30Sample 72 8 3.8 12.8 0.323 0.204 70/30 Sample 73 16 8.1 20.2 0.296 0.10170/30 Sample 74 3.3 1.0  8.9 0.519 0.431 70/30

In Table 7, 10% cumulative particle size from the side of a smallparticle size when the particle size distribution is measured by a laserdiffraction method is designated by D10 like the above-describedSample 1. Then, 50% cumulative particle size from the side of a smallparticle size is designated by D50 and 90% cumulative particle size fromthe side of a small particle size is designated by D90. Further, acarbonaceous material of a large particle size of spherical carbonaceousmaterials having different average particle sizes is called an anodeactive material 1. A carbonaceous material of a small particle size iscalled an anode active material 2.

Sample 69

In Sample 69, a battery was manufactured in the same manner as that ofSample 1 except that two kinds of natural graphite sphericallypulverized (referred to hereinafter as spherical natural graphite),having different particle sizes shown in Table 7, were used as the anodeactive material.

Sample 70

In Sample 70, a battery was manufactured in the same manner as that ofSample 1 except that two kinds of bulk mesophase artificial graphitespherically pulverized (referred to hereinafter as spherical bulkartificial graphite), having different particle sizes shown in Table 7,were used as the anode active material.

Sample 71

In sample 71, a battery was manufactured in the same manner as that ofSample 1 except that two kinds of hard carbon spherically pulverized(referred to hereinafter as spherical hard carbon), having differentparticle sizes shown in Table 7, were used as the anode active material.

Sample 72

In Sample 72, a battery was manufactured in the same manner as that ofSample 1 except that two kinds of spherical natural graphite havingdifferent particle sizes shown in Table 7 were used as the anode activematerial.

Sample 73

In Sample 73, a battery was manufactured in the same manner as that ofSample 1 except that two kinds of spherical bulk artificial graphitehaving different particle sizes shown in Table 7 were used as the anodeactive material.

Sample 74

In Sample 74, a battery was manufactured in the same manner as that ofSample 1 except that two kinds of spherical hard carbon having differentparticle sizes shown in Table 7 were used as the anode active material.

Then, for the batteries of Samples 69 to 74 manufactured as mentionedabove, the volume density of the anode composite mixture layer, theinitial charging and discharging efficiency, the initial dischargingcapacity, discharge load characteristics, and the discharging capacitymaintaining/retention ratio after a 500 cycle were measured.

The evaluated results of the volume density of the anode compositemixture layer, the initial charging and discharging efficiency, theinitial discharging capacity, the discharge load characteristics, andthe discharging capacity maintaining/retention ratio after a 500 cyclein Samples 69 to 74 are shown in Table 8.

TABLE 8 Volumetric Density of Anode Initial Charging/ Composite MixtureDischarging Initial Discharging Layer (g/cm³) Efficiency (%) Capacity(mAh) Sample 69 1.75 84 858 Sample 70 1.75 87 865 Sample 71 1.05 84 830Sample 72 1.70 74 755 Sample 73 1.70 71 701 Sample 74 0.94 68 675Capacity Maintaining/retention Discharging Load Ratio after 500 CycleCharacteristics (%) (%) Sample 69 85 76 Sample 70 91 83 Sample 71 86 80Sample 72 77 68 Sample 73 78 67 Sample 74 78 66

In Samples 69 to 74, the initial discharging capacity was evaluatedunder the same conditions as those of the above-described Sample 1 andSamples having the initial discharging capacity of 830 mAh or higherwere considered to be good products. The initial charging anddischarging efficiency was evaluated under the same conditions as thoseof the above-described Sample 1 and Samples having the initial chargingand discharging efficiency of 83% or higher were considered to be goodproducts. The discharge load characteristics were evaluated under thesame conditions as those of the above-described Sample 1 and Sampleshaving the discharge load characteristics of 85% or higher wereconsidered to be good products. The discharging capacitymaintaining/retention ratio after a 500 cycle was evaluated under thesame conditions as those of the above-described Sample 1 and Sampleshaving the discharging capacity maintaining/retention ratio after a 500cycle of 75% or higher were considered to be good products.

In Samples 69 and 70 shown in Table 7, particle distributionsrepresented by the expressions of log(D50)−log(D10) andlog(D90)−log(D50) in the carbonaceous material of a large particle sizeand the carbonaceous material of a small particle size have values notlarger than 0.22, and the particle size distribution areas of two kindsof spherical carbonaceous materials are controlled to be narrow ranges.In Sample 72, the particle size distribution of the spherical naturalgraphite of a small particle size represented by the expression oflog(D50)−log(D10) in the spherical natural graphite of a large particlesize and the spherical natural graphite of a small particle size islarger than 0.22, and the particle size distribution areas of two kindsof the spherical natural graphite are widened. Further, in Sample 73,the particle size distribution of the spherical bulk artificial graphiteof a large particle size represented by the expression oflog(D90)−log(D50) in the spherical bulk artificial graphite of the largeparticle size, and the particle size distribution of the spherical bulkartificial graphite of a small particle size represented by theexpression of log(D50)−log(D10) in the spherical bulk artificialgraphite of a small particle size are larger than 0.22. The particlesize distribution areas of two kinds of spherical bulk artificialgraphite are widened.

Then, as apparent from the evaluated results shown in Table 8, in Sample69 and Sample 70, the volume density of the anode composite mixturelayer, the initial charging and discharging efficiency, the initialdischarging capacity, the discharge load characteristics, and thedischarging capacity maintaining/retention ratio after a 500 cycle arehigher than those of Samples 72 and 73. As described above, it isrecognized that the particle size distributions of the sphericalcarbonaceous materials having different average particle sizescontrolled to be narrow like Samples 69 and 70 exhibit more excellentbattery characteristics.

In Samples 72 and 73, the particle size distributions represented by theexpressions of log(D50)−log(D10) and log(D90)−log(D50) in thecarbonaceous material of a large particle size and the carbonaceousmaterial of a small particle size have at least one value larger than0.22 like the above-described Samples 45 to 62 and the particle sizedistribution areas are widened. Thus, clearances in the anode compositemixture layer produced by the contact of two or more of sphericalcarbonaceous materials are not efficiently filled with the carbonaceousmaterial of a small particle size. Thus, it is difficult to improve thevolume density of the anode composite mixture layer. Therefore, inSamples 72 and 73, battery characteristics, such as the capacity of thebattery, are decreased.

On the other hand, in Samples 69 and 70, the particle size distributionsrepresented by the expressions of log(D50)−log(D10) andlog(D90)−log(D50) in the carbonaceous material of the large particlesize and the carbonaceous material of the small particle size havevalues not larger than 0.22, and the particle size distribution areas ofthe spherical carbonaceous materials having different average particlesizes are controlled to be narrow. Accordingly, an operational effect bythe carbonaceous material of a large particle size and an operationaleffect by the carbonaceous material of a small particle size can beobtained similarly to the above-described Sample 14. Therefore, inSamples 69 and 70, the volume density of the anode composite mixturelayer is increased to increase the capacity of the battery. Thus, thevolume density of the anode composite mixture layer is high, the initialcharging and discharging efficiency and the initial discharging capacitycan be increased, and an ionic resistance to the electrolyte of theanode side can be lowered to prevent the deterioration of the dischargeload characteristics and cyclic characteristics.

In Sample 71, shown in Table 7, particle distributions represented bythe expressions of log(D50)−log(D10) and log(D90)−log(D50) in thespherical hard carbon of a small particle size have values not largerthan 0.3 and the particle size distribution area of the spherical hardcarbon of a small particle size is controlled to be a narrow range. Onthe other hand, in Sample 74, the particle size distribution of thespherical hard carbon of a small particle size represented by theexpression of log(D50)−log(D10) in the spherical hard carbon of a smallparticle size is larger than 0.3 and the particle size distribution areaof the spherical hard carbon of a small particle size is widened.

Then, as apparent from the evaluated results shown in Table 8, in Sample71, the volume density of the anode composite mixture layer, the initialcharging and discharging efficiency, the initial discharging capacity,the discharge load characteristics, and the discharging capacitymaintaining/retention ratio after a 500 cycle are higher than those ofSample 74.

In Sample 74, the particle size distributions represented by theexpressions of log(D50)−log(D10) and log(D90)−log(D50) in the sphericalhard carbon of a small particle size have values larger than 0.22 likethe above-described Samples 45 to 62, and the particle size distributionareas are widened. Thus, clearances in the anode composite mixturelayer, produced by the contact of two or more of spherical hard carbons,are hardly efficiently filled with the spherical hard carbons of a smallparticle size. Thus, it is difficult to improve the volume density ofthe anode composite mixture layer. Therefore, in Sample 74, batterycharacteristics such as the capacity of the battery are decreased.

On the other hand, in Sample 71, the particle size distributionsrepresented by the expressions of log(D50)−log(D10) andlog(D90)−log(D50) in the spherical hard carbon of a large particle sizeand the spherical hard carbon of a small particle size have values notlarger than 0.3, and the particle size distribution areas of two kindsof spherical hard carbons are controlled to be narrow. Accordingly, anoperational effect by the spherical hard carbon of a large particle sizeand an operational effect by the spherical hard carbon of a smallparticle size can be obtained similarly to the above-described Sample14. Therefore, in Sample 71, the volume density of the anode compositemixture layer is increased to increase the capacity of the battery.Thus, the volume density of the anode composite mixture layer is high,the initial charging and discharging efficiency and the initialdischarging capacity can be increased, and an ionic resistance to theelectrolyte of the anode side can be lowered to prevent thedeterioration of the discharge load characteristics and cycliccharacteristics.

As described above, the battery is manufactured by changing the anodeactive material from the spherical graphite to the sphericalcarbonaceous material. At this time, it is extremely effective tocontrol the particle size distribution areas of the sphericalcarbonaceous materials having different average particle sizes to benarrow in manufacturing a battery having a high volume density of ananode composite mixture layer and excellent in its batterycharacteristics such as charging and discharging efficiencycharacteristics, discharging capacity characteristics, discharge loadcharacteristics, and charging and discharging cyclic characteristics.

The present invention is not limited the above-described embodiments andit is obviously possible for a person with ordinary skill in the art toperform various changes, substitutions or the equivalence theretowithout departing attached claims and the gist thereof.

INDUSTRIAL APPLICABILITY

As mentioned above, according to the present invention, the anode activematerial is composed of a mixture of a plurality of kinds ofcarbonaceous materials having different average particle sizes. Theparticle size distribution areas of the plural kinds of carbonaceousmaterials are controlled to be narrow. Thus, the carbonaceous materialof a large particle size of the carbonaceous materials having differentaverage particle sizes in the anode active material decreases a surfacearea to a volume, so that a reactivity with a non-aqueous electrolytecan be decreased to suppress the deterioration of the capacity of abattery. Further, according to the present invention, the carbonaceousmaterial of the large particle size increases the volume relative to thesurface area, so that a bulk part whose crystallization is advancedbecomes large relative to the carbonaceous material of a small particlesize. Thus, the amount of lithium storage is increased to increase thecapacity of the battery or energy density. Further, according to thepresent invention, the carbonaceous material of a large particle sizeforms clearances of suitable sizes in the anode to retain a non-aqueouselectrolyte. Thus, an ionic resistance to the non-aqueous electrolyte ofthe anode side can be lowered to prevent the deterioration of batterycharacteristics.

According to the present invention, the clearances in the anode areefficiently filled with the carbonaceous material of a small particlesize having a large surface area relative to the volume of the anodeamong the carbonaceous materials having different average particle sizesin the anode active material while the carbonaceous material of a smallparticle size leaves spaces capable of retaining a suitable amount ofnon-aqueous electrolyte. Consequently the volume density of the anodecan be improved to increase the capacity of the battery or energydensity.

Therefore, according to the present invention, the non-aqueouselectrolyte battery in which the energy density can be increased withoutdeteriorating the battery characteristics is obtained.

1. A non-aqueous electrolyte battery comprising: a cathode having acathode active material containing lithium; an anode having an anodeactive material capable of being doped with/dedoped from lithium; and anon-aqueous electrolyte including electrolyte salt, wherein the anodeactive material is composed of a mixture of a plurality of sphericalcarbonaceous materials having a particle size distribution satisfyingthe relationship represented by expressions (1) and (2) below:log(D50)−log(D10)≦0.3  (1)log(D90)−log(D50)≦0.3  (2) wherein the units of D are in units of μm andthe logarithms have bases of 10; and wherein D10, D50, and D90 representparticle sizes of the mixture of the plurality of spherical carbonaceousmaterials, and where D10 represents a particle size such that 10% of theparticles in the mixture of the plurality of spherical carbonaceousmaterials are smaller than D10, D50 represents a particle size such that50% of the particles in the mixture of the plurality of sphericalcarbonaceous materials are smaller than D50, and D90 represents aparticle size such that 90% of the particles in the mixture of theplurality of spherical carbonaceous materials are smaller than D90. 2.The non-aqueous electrolyte battery according to claim 1, wherein, theanode active material has a particle size distribution satisfying therelationship represented by expressions (3) and (4) below:log(DL50)−log(DL10)≦0.22  (3)log(DL90)−log(DL50)≦0.22  (4) wherein the units of DL are in units of μmand the logarithms have bases of 10; and wherein DL10, DL50, and DL90represent particle sizes of the graphite of large particle size, andwhere DL10 represents a particle size such that 10% of the particles ofgraphite of large particle size are smaller than DL10, DL50 represents aparticle size such that 50% of the particles of graphite of largeparticle size are smaller than DL50, and DL90 represents a particle sizesuch that 90% of the particles of graphite of large particle size aresmaller than DL90; and the anode active material has a particle sizedistribution satisfying the relationship represented by expressions (5)and (6) below:log(DS50)−log(DS10)≦0.22  (5)log(DS90)−log(DS50)≦0.22  (6) wherein the units of DS are in units of μmand the logarithms have bases of 10; and wherein DS10, DS50, and DS90represent particle sizes of the graphite of small particle size, andwhere DS10 represents a particle size such that 10% of the particles ofgraphite of small particle size are smaller than DS10, DS50 represents aparticle size such that 50% of the particles of graphite of smallparticle size are smaller than DS50, and DS90 represents a particle sizesuch that 90% of the particles of graphite of small particle size aresmaller than DS90.
 3. The non-aqueous electrolyte battery according toclaim 1, wherein, the anode active material is composed of a mixture atleast including spherical graphite of large particle size whose averageparticle size is located within a range of 20 μm or larger and 40 μm orsmaller and spherical graphite of small particle size whose averageparticle size is located within a range of 5 μm or larger and 16 μm orsmaller, and the average particle size of the spherical graphite ofsmall particle size is 0.55 times the average particle size of thespherical graphite of large particle size, or smaller.